Sarfaraz Ahmad | Aligarh Muslim University (original) (raw)
Papers by Sarfaraz Ahmad
![Research paper thumbnail of Cytotoxicity and mutagenicity of dibenzo[a,l]pyrene and (±)-dibenzo[a,l]pyrene-11,12-dihydrodiol in V79MZ cells co-expressing either hCYP1A1 or hCYP1B1 together with human glutathione-S-transferase A1](https://attachments.academia-assets.com/46969705/thumbnails/1.jpg)
](Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 2007
We have used V79MZ hamster lung fibroblasts stably transfected with human cytochrome P450-1A1 (hC... more We have used V79MZ hamster lung fibroblasts stably transfected with human cytochrome P450-1A1 (hCYP1A1; cell line designated V79MZh1A1) or P450-1B1 (hCYP1B1; cell line designated V79MZh1B1) alone, or in combination with human GST alpha-1 (hGSTA1), in order to examine GST protection against cytotoxicity and mutagenicity of dibenzo[a,l]pyrene (DBP) and the intermediate dihydrodiol metabolite (+/−)-DBP-11,12-dihydrodiol (DBPD). At comparable expression levels of hCYP1A1 and hCYP1B1, both DBP and DBPD were more cytotoxic in V79MZ1A1 (IC 50 = 2.7 nM and 0.7 nM, respectively) than in V79MZh1B1 (IC 50 = 6.0 nM and 4.8 nM, respectively). In contrast, both DBP and DBPD were 2-fold to 4-fold more mutagenic in V79MZh1B1 than in V79MZ1A1. Co-expression of hGSTA1 with hCYP1A1 decreased DBP cytotoxicity 2-fold compared to V79MZh1A1 with hCYP1A1 alone, and provided a small, yet still statistically significant, 1.3-fold protection against DBPD. Protection against mutagenicity of these compounds was comparable to that for cytotoxicity in cells expressing hCYP1A1. In V79MZh1B1 cells, co-expression of hGSTA1 conferred up to 5-fold protection against DBP cytotoxicity, and up to 9-fold protection against the (+/−)-DBP-dihydrodiol cytotoxicity relative to the cells expressing hCYP1B1 alone. Co-expression of hGSTA1 also reduced mutagenicity of DBP or its dihydrodiol to a lesser extent (1.3-fold to 1.8-fold) than the protection against cytotoxicity in cells expressing hCYP1B1. These findings demonstrate that the protective efficacy of hGSTA1 against DBP and DBPD toxicity is variable, depending on the compound or metabolite present, the specific cytochrome P450 isozyme expressed, and the specific cellular damage endpoint examined.
Renin Angiotensin System and Cardiovascular Disease, 2009
The discovery of angiotensin-(1-7) [Ang-(1-7)] in 1988 represented the first deviation from the t... more The discovery of angiotensin-(1-7) [Ang-(1-7)] in 1988 represented the first deviation from the traditional biochemical cascade of forming bioactive angiotensin peptides. Prior to that time, the biological actions of angiotensin II (Ang II) were being investigated as it relates to cardiovascular function, including hypertension, cardiac hypertrophy and failure, as well as biological actions in the brain and kidney. We now know that Ang II elicits a whole host of actions both within and outside of the cardiovascular system. Furthermore, the discovery of Ang-(1-7) by our laboratory was also the first indication of a biologically active angiotensin peptide that further studies revealed served to counter-balance the actions of Ang II. This chapter reviews the data demonstrating the role of the vasodepressor axis of the renin angiotensin system in the regulation of cardiovascular function and the new data that shows the existence of angiotensin-(1-12) as a novel alternate substrate for the production of angiotensin peptides. The ultimate role of this discovery, as well as the continuing elucidation of mechanisms pertaining to RAS physiology, will likely be clarified in the coming years, in hopes of improving the treatment of cardiovascular disease.
PLOS One, 2011
Background: Angiotensin-(1-12) ] functions as an endogenous substrate for the productions of Ang ... more Background: Angiotensin-(1-12) ] functions as an endogenous substrate for the productions of Ang II and Ang-(1-7) by a non-renin dependent mechanism. This study evaluated whether Ang-(1-12) is incorporated by neonatal cardiac myocytes and the enzymatic pathways of 125 I-Ang-(1-12) metabolism in the cardiac myocyte medium from WKY and SHR rats.
American Journal of Nephrology, 2010
lol prevented salt-induced kidney injury and associated proteinuria in SHR through a blood pressu... more lol prevented salt-induced kidney injury and associated proteinuria in SHR through a blood pressure-independent mechanism. Its protective effects may be related to reduction in oxidative stress, increases in neuronal NOS and restoration of angiotensin II type 1/mas receptor balance.
Toxicology Letters, 2008
The environmental carcinogen 5-methylchrysene (5MC) can be activated to mutagenic metabolites by ... more The environmental carcinogen 5-methylchrysene (5MC) can be activated to mutagenic metabolites by several isozymes of cytochrome P-450 (CYP). The resulting reactive diol-epoxides can be detoxified via conjugation by glutathione S-transferases (GST). We investigated whether expression of human glutathione S-transferase P1 (hGSTP1) would differentially protect cells against the cytotoxicity or mutagenicity of 5MC or its 1,2-dihydrodiol intermediate (5MC-1,2-diol) in V79MZ cells with activation via stably transfected human CYP1B1 (hCYP1B1) as compared to activation by human CYP1A1 (hCYP1A1). The parent compound 5MC was only 2-fold more cytotoxic in the CYP-expressing cell lines than in the V79MZ parental cell line, while 5MC-1,2-dihydrodiol was more than 30-fold more cytotoxic in CYP-transfected cells compared to V79MZ cells. Cells co-expressing either hCYP1B1 or hCYP1A1 together with hGSTP1 were 2-fold less sensitive to 5MC or 5MC-1,2-diol cytotoxicity than their CYP-only parent lines. The 5MC was highly mutagenic with similar potency in both hCYP-transfected cell lines, while 5MC-1,2-diol was 2-fold more mutagenic in hCYP1B1-transfected cells as compared to hCYP1A1 cells. Coexpression of hGSTP1 with either hCYP reduced 5MC or 5MC-1,2-diol mutagenicity by 1.4–4.5-fold compared to the corresponding hCYP-only expressing cell lines. The greater protection against mutagenicity of 5MC is in contrast to our previous studies in which we found greater protection by hGSTP1 against cytotoxicity than mutagenicity of benzo[a]pyrene in cells co-expressing hCYP1A1. Protection against mutagenicity by hGSTP1 was greater with activation of either compound by hCYP1B1 than with hCYP1A1 activation. These studies show that the relative efficacy of protection by hGSTP1 against mutagenicity of 5MC or 5MC-1,2-diol is in part determined by the specific CYP pathway that catalyzes activation to the toxic or mutagenic metabolites.
Biochemical and Biophysical Research Communications, 1999
The reactive metabolite(s) responsible for the expression of benzene toxicity is not clearly know... more The reactive metabolite(s) responsible for the expression of benzene toxicity is not clearly known despite extensive information on the metabolism and hematotoxicity of benzene. It is now widely believed that hematotoxicity of benzene is due to the concerted action of several metabolites which arise from multiple pathways of benzene. In our earlier study, we proposed iron polyphenol chelates as possible toxic metabolites of benzene due to their prooxidant activity. In continuation, we demonstrate the formation of an iron and 1,2,4-benzenetriol (BT) complex, when added together in an acetate buffer, 0.1 M, pH 5.6, by sephadex G-10 column chromatography. It was also observed that iron released from ferritin in the presence of BT formed a complex with BT.
![Research paper thumbnail of Cytotoxicity and mutagenicity of dibenzo[ a,l]pyrene and (±)-dibenzo[ a,l]pyrene-11,12-dihydrodiol in V79MZ cells co-expressing either hCYP1A1 or hCYP1B1 together with human glutathione- S-transferase A1](https://attachments.academia-assets.com/46969686/thumbnails/1.jpg)
](Mutation Research-fundamental and Molecular Mechanisms of Mutagenesis, 2007
We have used V79MZ hamster lung fibroblasts stably transfected with human cytochrome P450-1A1 (hC... more We have used V79MZ hamster lung fibroblasts stably transfected with human cytochrome P450-1A1 (hCYP1A1; cell line designated V79MZh1A1) or P450-1B1 (hCYP1B1; cell line designated V79MZh1B1) alone, or in combination with human glutathione-S-transferase (GST) alpha-1 (hGSTA1), in order to examine GST protection against cytotoxicity and mutagenicity of dibenzo[a,l]pyrene (DBP) and the intermediate dihydrodiol metabolite (±)-DBP-11,12-dihydrodiol (DBPD). At comparable expression levels of hCYP1A1 and hCYP1B1, both DBP and DBPD were more cytotoxic in V79MZ1A1 (IC50 = 2.7 and 0.7 nM, respectively) than in V79MZh1B1 (IC50 = 6.0 and 4.8 nM, respectively). In contrast, both DBP and DBPD were two- to four-fold more mutagenic in V79MZh1B1 than in V79MZ1A1. Co-expression of hGSTA1 with hCYP1A1 decreased DBP cytotoxicity two-fold compared to V79MZh1A1 with hCYP1A1 alone, and provided a small, yet still statistically significant, 1.3-fold protection against DBPD. Protection against mutagenicity of these compounds was comparable to that for cytotoxicity in cells expressing hCYP1A1. In V79MZh1B1 cells, co-expression of hGSTA1 conferred up to five-fold protection against DBP cytotoxicity, and up to nine-fold protection against the (±)-DBP-dihydrodiol cytotoxicity relative to the cells expressing hCYP1B1 alone. Co-expression of hGSTA1 also reduced mutagenicity of DBP or its dihydrodiol to a lesser extent (1.3–1.8-fold) than the protection against cytotoxicity in cells expressing hCYP1B1. These findings demonstrate that the protective efficacy of hGSTA1 against DBP and DBPD toxicity is variable, depending on the compound or metabolite present, the specific cytochrome P450 isozyme expressed, and the specific cellular damage endpoint examined.
Toxicology, 2000
Glutathionyl hydroquinone (GHQ), a highly reactive metabolite of benzene, has been implicated as ... more Glutathionyl hydroquinone (GHQ), a highly reactive metabolite of benzene, has been implicated as a causative intermediate of benzene toxicity. To substantiate, the bioreactivity of GHQ was investigated under in vitro and in vivo conditions using end points, characteristic of benzene toxicity. Under in vitro conditions, the presence of GHQ: (a) linearly increased the release of aldehydic products from l-glutamate or deoxyuridine at GHQ concentrations of 5–25 μM and from rat liver homogenates at GHQ concentrations of 50–250 μM; (b) cleaved plasmid pUC 18 supercoiled DNA through a single strand nick to yield open circular relaxed DNA, and through a double strand cut to give out linear DNA at GHQ concentrations of 25–200 μM, with evidence of protection by catalase and superoxide dismutase; and (c) induced cross-linking and polymerization of lymphocyte nuclear DNA through in situ generation of GHQ, which was protected by pretreatment of lymphocytes with N-ethylmaleimide. In vivo exposure of Swiss albino mice to GHQ (100 mg/kg, intraperitoneally once daily for 30 days) resulted in significant increase of liver weight and inhibition of mitotic index in the bone marrow. The other test parameters, namely spleen weight, hematological indices, hepatic sulphahydryl content and nonenzymatic lipid peroxidation, and chromosomal aberrations in the bone marrow were, however, unaffected by GHQ treatment. The observations indicate pro-oxidant and cytotoxic potential of GHQ, mediated by the reactive oxygen species generated during the course of its auto-oxidation. Bioreactivity of GHQ with cellular macromolecules in vitro and inhibition of mitotic index of bone marrow on in vivo exposure have relevance to benzene toxicity, although in situ generation of GHQ at the site of action appears critical in bringing about hematological and chromosomal effects that were probably spared due to rapid metabolic disposition and, consequently, poor bioavailability of intraperitoneally administered GHQ.
Kidney International, 2005
Background. The activity of the organic anion transporter 1 (OAT1) has been implicated recently i... more Background. The activity of the organic anion transporter 1 (OAT1) has been implicated recently in the basolateral uptake of thiol conjugates of inorganic mercury in renal proximal tubular cells. However, very little is known about the role of OAT1 in the renal epithelial transport of organic forms of mercury, such as methylmercury (CH 3 Hg + ), especially when it is in the form of the cysteine (Cys) S-conjugate of methylmercury (CH 3 Hg-Cys), which is believed to be a biologically relevant form of mercury.
Toxicology Letters, 2002
Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human l... more Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human liver ferritin (HLF) with or without the presence of ascorbic acid. With ascorbic acid the rate of iron release from HLF by DMA(V) was intermediate (3.37 nM/min, P<0.05) and by DMA(III) was much higher (16.3 nM/min, P<0.001). No pBR322 plasmid DNA damage was observed from in vitro exposure to arsenate (iAs(V)), arsenite (iAs(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)) or DMA(V) alone. DNA damage was observed following DMA(III) exposure; coexposure to DMA(III) and HLF caused more DNA damage; considerably higher amounts of DNA damage was caused by coexposure of DMA(III), HLF and ascorbic acid. Diethylenetriaminepentaacetic acid (an iron chelator), significantly inhibited DNA damage. Addition of catalase (which can increase Fe2+ concentrations) further increased the plasmid DNA damage. Iron-dependent DNA damage could be a mechanism of action of human arsenic carcinogenesis.
Toxicology and Applied Pharmacology, 2003
Cadmium (Cd) is an industrial and environmental pollutant that affects adversely a number of orga... more Cadmium (Cd) is an industrial and environmental pollutant that affects adversely a number of organs in humans and other mammals, including the kidneys, liver, lungs, pancreas, testis, and placenta. The liver and kidneys, which are the primary organs involved in the elimination of systemic Cd, are especially sensitive to the toxic effects of Cd. Because Cd ions possess a high affinity for sulfhydryl groups and thiolate anions, the cellular and molecular mechanisms involved in the handling and toxicity of Cd in target organs can be defined largely by the molecular interactions that occur between Cd ions and various sulfhydryl-containing molecules that are present in both the intracellular and extracellular compartments. A great deal of scientific data have been collected over the years to better define the toxic effects of Cd in the primary target organs. Notwithstanding all of the new developments made and information gathered, it is surprising that very little is known about the cellular and molecular mechanisms involved in the uptake, retention, and elimination of Cd in target epithelial cells. Therefore, the primary purpose of this review is to summarize and put into perspective some of the more salient current findings, assertions, and hypotheses pertaining to the transport and handling of Cd in the epithelial cells of target organs. Particular attention has been placed on the molecular mechanisms involved in the absorption, retention, and secretion of Cd in small intestinal enterocytes, hepatocytes, and tubular epithelial cells lining both proximal and distal portions of the nephron. The purpose of this review is not only to provide a summary of published findings but also to provide speculations and testable hypotheses based on contemporary findings made in other areas of research, with the hope that they may promote and serve as the impetus for future investigations designed to define more precisely the cellular mechanisms involved in the transport and handling of Cd within the body.
Toxicology Letters, 2003
Many modes of action for arsenic carcinogenesis have been proposed, but few theories have a subst... more Many modes of action for arsenic carcinogenesis have been proposed, but few theories have a substantial mass of supporting data. Three stronger theories of arsenic carcinogenesis are production of chromosomal abnormalities, promotion of carcinogenesis and oxidative stress. This article presents the oxidative stress theory along with some supporting experimental data. In the area of which arsenic species is causually active, recent data have suggested that trivalent methylated arsenic metabolites, particularly monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III)), have a great deal of biological activity. Some evidence now indicates that these trivalent, methylated, and relatively less ionizable arsenic metabolites may be unusually capable of interacting with cellular targets such as proteins and even DNA. Thus for inorganic arsenic, oxidative methylation followed by reduction to trivalency may be a activation, rather than a detoxification pathway. This would be particularly true for arsenate. In forming toxic and carcinogenic arsenic species, reduction from the pentavalent state to the trivalent state may be as or more important than methylation of arsenic.
Toxicology, 1994
Bleomycin-dependent degradation of DNA in bone marrow cells was studied in vitro in the presence ... more Bleomycin-dependent degradation of DNA in bone marrow cells was studied in vitro in the presence of iron or iron polyphenol chelates which are formed during biotransformation of benzene. Iron polyphenol chelates markedly enhanced bleomycin-dependent DNA degradation in comparison to iron alone. About 1.5 and 2.5-fold increase was observed in the presence of iron hydroquinone (HQ) chelate and iron 1,2,4-benzenetriol (BT) chelate, respectively. Endogenous iron chelators such as glutamate, citrate, aspartate, glycine, cysteine, dithiothreitol, AMP, ADP and ATP did not enhance iron-catalysed bleomycin-dependent degradation of DNA. By bleomycin assay, the recovery of iron polyphenol chelate added externally to bone marrow lysate was complete. However, the presence of iron polyphenol chelate resulted in less thiobarbituric acid reactive products from glutamate or brain homogenate than with iron alone. The optical spectra of BT were modified in the presence of ferrous sulphate, revealing a new absorption peak at 259 nm indicating complexation with iron. Thus, the iron polyphenol chelate, on one hand, is a more potent DNA cleaving agent in the presence of bleomycin, and on the other hand, it is a less effective free radical generator as compared to iron alone.
Advances in Pharmacology, 2010
The contribution of the renin angiotensin system to physiology and pathology is undergoing a rapi... more The contribution of the renin angiotensin system to physiology and pathology is undergoing a rapid reconsideration of its mechanisms from emerging new concepts implicating angiotensin-converting enzyme 2 and angiotensin-(1-7) as new elements negatively influencing the vasoconstrictor, trophic, and pro-inflammatory actions of angiotensin II. This component of the system acts to oppose the vasoconstrictor and proliferative effects on angiotensin II through signaling mechanisms mediated by the mas receptor. In addition, a reduced expression of the vasodepressor axis composed by angiotensin-converting enzyme 2 and angiotensin-(1-7) may contribute to the expression of essential hypertension, the remodeling of heart and renal function associated with this disease, and even the physiology of pregnancy and the development of eclampsia.
Toxicology Letters, 2002
Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human l... more Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human liver ferritin (HLF) with or without the presence of ascorbic acid. With ascorbic acid the rate of iron release from HLF by DMA(V) was intermediate (3.37 nM/min, PB 0.05) and by DMA(III) was much higher (16.3 nM/min, P B 0.001). No pBR322 plasmid DNA damage was observed from in vitro exposure to arsenate (iAs(V)), arsenite (iAs(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)) or DMA(V) alone. DNA damage was observed following DMA(III) exposure; coexposure to DMA(III) and HLF caused more DNA damage; considerably higher amounts of DNA damage was caused by coexposure of DMA(III), HLF and ascorbic acid. Diethylenetriaminepentaacetic acid (an iron chelator), significantly inhibited DNA damage. Addition of catalase (which can increase Fe 2 + concentrations) further increased the plasmid DNA damage. Iron-dependent DNA damage could be a mechanism of action of human arsenic carcinogenesis.
Toxicology and Applied Pharmacology, 2003
Cadmium (Cd) is an industrial and environmental pollutant that affects adversely a number of orga... more Cadmium (Cd) is an industrial and environmental pollutant that affects adversely a number of organs in humans and other mammals, including the kidneys, liver, lungs, pancreas, testis, and placenta. The liver and kidneys, which are the primary organs involved in the elimination of systemic Cd, are especially sensitive to the toxic effects of Cd. Because Cd ions possess a high affinity for sulfhydryl groups and thiolate anions, the cellular and molecular mechanisms involved in the handling and toxicity of Cd in target organs can be defined largely by the molecular interactions that occur between Cd ions and various sulfhydryl-containing molecules that are present in both the intracellular and extracellular compartments. A great deal of scientific data have been collected over the years to better define the toxic effects of Cd in the primary target organs. Notwithstanding all of the new developments made and information gathered, it is surprising that very little is known about the cellular and molecular mechanisms involved in the uptake, retention, and elimination of Cd in target epithelial cells. Therefore, the primary purpose of this review is to summarize and put into perspective some of the more salient current findings, assertions, and hypotheses pertaining to the transport and handling of Cd in the epithelial cells of target organs. Particular attention has been placed on the molecular mechanisms involved in the absorption, retention, and secretion of Cd in small intestinal enterocytes, hepatocytes, and tubular epithelial cells lining both proximal and distal portions of the nephron. The purpose of this review is not only to provide a summary of published findings but also to provide speculations and testable hypotheses based on contemporary findings made in other areas of research, with the hope that they may promote and serve as the impetus for future investigations designed to define more precisely the cellular mechanisms involved in the transport and handling of Cd within the body.
Toxicology, 2000
Glutathionyl hydroquinone (GHQ), a highly reactive metabolite of benzene, has been implicated as ... more Glutathionyl hydroquinone (GHQ), a highly reactive metabolite of benzene, has been implicated as a causative intermediate of benzene toxicity. To substantiate, the bioreactivity of GHQ was investigated under in vitro and in vivo conditions using end points, characteristic of benzene toxicity. Under in vitro conditions, the presence of GHQ: (a) linearly increased the release of aldehydic products from L-glutamate or deoxyuridine at GHQ concentrations of 5-25 mM and from rat liver homogenates at GHQ concentrations of 50 -250 mM; (b) cleaved plasmid pUC 18 supercoiled DNA through a single strand nick to yield open circular relaxed DNA, and through a double strand cut to give out linear DNA at GHQ concentrations of 25 -200 mM, with evidence of protection by catalase and superoxide dismutase; and (c) induced cross-linking and polymerization of lymphocyte nuclear DNA through in situ generation of GHQ, which was protected by pretreatment of lymphocytes with N-ethylmaleimide. In vivo exposure of Swiss albino mice to GHQ (100 mg/kg, intraperitoneally once daily for 30 days) resulted in significant increase of liver weight and inhibition of mitotic index in the bone marrow. The other test parameters, namely spleen weight, hematological indices, hepatic sulphahydryl content and nonenzymatic lipid peroxidation, and chromosomal aberrations in the bone marrow were, however, unaffected by GHQ treatment. The observations indicate pro-oxidant and cytotoxic potential of GHQ, mediated by the reactive oxygen species generated during the course of its auto-oxidation. Bioreactivity of GHQ with cellular macromolecules in vitro and inhibition of mitotic index of bone marrow on in vivo exposure have relevance to benzene toxicity, although in situ generation of GHQ at the site of action appears critical in bringing about hematological and chromosomal effects that were probably spared due to rapid metabolic disposition and, consequently, poor bioavailability of intraperitoneally administered GHQ.
PLoS ONE, 2011
Background: Angiotensin-(1-12) ] functions as an endogenous substrate for the productions of Ang ... more Background: Angiotensin-(1-12) ] functions as an endogenous substrate for the productions of Ang II and Ang-(1-7) by a non-renin dependent mechanism. This study evaluated whether Ang-(1-12) is incorporated by neonatal cardiac myocytes and the enzymatic pathways of 125 I-Ang-(1-12) metabolism in the cardiac myocyte medium from WKY and SHR rats.
PLoS ONE, 2013
The cardioprotective effects of estrogen are well recognized, but the mechanisms remain poorly un... more The cardioprotective effects of estrogen are well recognized, but the mechanisms remain poorly understood. Accumulating evidence suggests that the local cardiac renin-angiotensin system (RAS) is involved in the development and progression of cardiac hypertrophy, remodeling, and heart failure. Estrogen attenuates the effects of an activated circulating RAS; however, its role in regulating the cardiac RAS is unclear. Bilateral oophorectomy (OVX; n = 17) or sham-operation (Sham; n = 13) was performed in 4-week-old, female mRen2.Lewis rats. At 11 weeks of age, the rats were randomized and received either 17 bestradiol (E2, 36 mg/pellet, 60-day release, n = 8) or vehicle (OVX-V, n = 9) for 4 weeks. The rats were sacrificed, and blood and hearts were used to determine protein and/or gene expression of circulating and tissue RAS components. E2 treatment minimized the rise in circulating angiotensin (Ang) II and aldosterone produced by loss of ovarian estrogens. Chronic E2 also attenuated OVX-associated increases in cardiac Ang II, Ang-(1-7) content, chymase gene expression, and mast cell number. Neither OVX nor OVX+E2 altered cardiac expression or activity of renin, angiotensinogen, angiotensin-converting enzyme (ACE), and Ang II type 1 receptor (AT1R). E2 treatment in OVX rats significantly decreased gene expression of MMP-9, ACE2, and Ang-(1-7) mas receptor, in comparison to sham-operated and OVX littermates. E2 treatment appears to inhibit upsurges in cardiac Ang II expression in the OVX-mRen2 rat, possibly by reducing chymase-dependent Ang II formation. Further studies are warranted to determine whether an E2-mediated reduction in cardiac chymase directly contributes to this response in OVX rats. Citation: Wang H, Jessup JA, Zhao Z, Da Silva J, Lin M, et al. (2013) Characterization of the Cardiac Renin Angiotensin System in Oophorectomized and Estrogen-Replete mRen2.Lewis Rats. PLoS ONE 8(10): e76992.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 2007
We have used V79MZ hamster lung fibroblasts stably transfected with human cytochrome P450-1A1 (hC... more We have used V79MZ hamster lung fibroblasts stably transfected with human cytochrome P450-1A1 (hCYP1A1; cell line designated V79MZh1A1) or P450-1B1 (hCYP1B1; cell line designated V79MZh1B1) alone, or in combination with human GST alpha-1 (hGSTA1), in order to examine GST protection against cytotoxicity and mutagenicity of dibenzo[a,l]pyrene (DBP) and the intermediate dihydrodiol metabolite (+/−)-DBP-11,12-dihydrodiol (DBPD). At comparable expression levels of hCYP1A1 and hCYP1B1, both DBP and DBPD were more cytotoxic in V79MZ1A1 (IC 50 = 2.7 nM and 0.7 nM, respectively) than in V79MZh1B1 (IC 50 = 6.0 nM and 4.8 nM, respectively). In contrast, both DBP and DBPD were 2-fold to 4-fold more mutagenic in V79MZh1B1 than in V79MZ1A1. Co-expression of hGSTA1 with hCYP1A1 decreased DBP cytotoxicity 2-fold compared to V79MZh1A1 with hCYP1A1 alone, and provided a small, yet still statistically significant, 1.3-fold protection against DBPD. Protection against mutagenicity of these compounds was comparable to that for cytotoxicity in cells expressing hCYP1A1. In V79MZh1B1 cells, co-expression of hGSTA1 conferred up to 5-fold protection against DBP cytotoxicity, and up to 9-fold protection against the (+/−)-DBP-dihydrodiol cytotoxicity relative to the cells expressing hCYP1B1 alone. Co-expression of hGSTA1 also reduced mutagenicity of DBP or its dihydrodiol to a lesser extent (1.3-fold to 1.8-fold) than the protection against cytotoxicity in cells expressing hCYP1B1. These findings demonstrate that the protective efficacy of hGSTA1 against DBP and DBPD toxicity is variable, depending on the compound or metabolite present, the specific cytochrome P450 isozyme expressed, and the specific cellular damage endpoint examined.
Renin Angiotensin System and Cardiovascular Disease, 2009
The discovery of angiotensin-(1-7) [Ang-(1-7)] in 1988 represented the first deviation from the t... more The discovery of angiotensin-(1-7) [Ang-(1-7)] in 1988 represented the first deviation from the traditional biochemical cascade of forming bioactive angiotensin peptides. Prior to that time, the biological actions of angiotensin II (Ang II) were being investigated as it relates to cardiovascular function, including hypertension, cardiac hypertrophy and failure, as well as biological actions in the brain and kidney. We now know that Ang II elicits a whole host of actions both within and outside of the cardiovascular system. Furthermore, the discovery of Ang-(1-7) by our laboratory was also the first indication of a biologically active angiotensin peptide that further studies revealed served to counter-balance the actions of Ang II. This chapter reviews the data demonstrating the role of the vasodepressor axis of the renin angiotensin system in the regulation of cardiovascular function and the new data that shows the existence of angiotensin-(1-12) as a novel alternate substrate for the production of angiotensin peptides. The ultimate role of this discovery, as well as the continuing elucidation of mechanisms pertaining to RAS physiology, will likely be clarified in the coming years, in hopes of improving the treatment of cardiovascular disease.
PLOS One, 2011
Background: Angiotensin-(1-12) ] functions as an endogenous substrate for the productions of Ang ... more Background: Angiotensin-(1-12) ] functions as an endogenous substrate for the productions of Ang II and Ang-(1-7) by a non-renin dependent mechanism. This study evaluated whether Ang-(1-12) is incorporated by neonatal cardiac myocytes and the enzymatic pathways of 125 I-Ang-(1-12) metabolism in the cardiac myocyte medium from WKY and SHR rats.
American Journal of Nephrology, 2010
lol prevented salt-induced kidney injury and associated proteinuria in SHR through a blood pressu... more lol prevented salt-induced kidney injury and associated proteinuria in SHR through a blood pressure-independent mechanism. Its protective effects may be related to reduction in oxidative stress, increases in neuronal NOS and restoration of angiotensin II type 1/mas receptor balance.
Toxicology Letters, 2008
The environmental carcinogen 5-methylchrysene (5MC) can be activated to mutagenic metabolites by ... more The environmental carcinogen 5-methylchrysene (5MC) can be activated to mutagenic metabolites by several isozymes of cytochrome P-450 (CYP). The resulting reactive diol-epoxides can be detoxified via conjugation by glutathione S-transferases (GST). We investigated whether expression of human glutathione S-transferase P1 (hGSTP1) would differentially protect cells against the cytotoxicity or mutagenicity of 5MC or its 1,2-dihydrodiol intermediate (5MC-1,2-diol) in V79MZ cells with activation via stably transfected human CYP1B1 (hCYP1B1) as compared to activation by human CYP1A1 (hCYP1A1). The parent compound 5MC was only 2-fold more cytotoxic in the CYP-expressing cell lines than in the V79MZ parental cell line, while 5MC-1,2-dihydrodiol was more than 30-fold more cytotoxic in CYP-transfected cells compared to V79MZ cells. Cells co-expressing either hCYP1B1 or hCYP1A1 together with hGSTP1 were 2-fold less sensitive to 5MC or 5MC-1,2-diol cytotoxicity than their CYP-only parent lines. The 5MC was highly mutagenic with similar potency in both hCYP-transfected cell lines, while 5MC-1,2-diol was 2-fold more mutagenic in hCYP1B1-transfected cells as compared to hCYP1A1 cells. Coexpression of hGSTP1 with either hCYP reduced 5MC or 5MC-1,2-diol mutagenicity by 1.4–4.5-fold compared to the corresponding hCYP-only expressing cell lines. The greater protection against mutagenicity of 5MC is in contrast to our previous studies in which we found greater protection by hGSTP1 against cytotoxicity than mutagenicity of benzo[a]pyrene in cells co-expressing hCYP1A1. Protection against mutagenicity by hGSTP1 was greater with activation of either compound by hCYP1B1 than with hCYP1A1 activation. These studies show that the relative efficacy of protection by hGSTP1 against mutagenicity of 5MC or 5MC-1,2-diol is in part determined by the specific CYP pathway that catalyzes activation to the toxic or mutagenic metabolites.
Biochemical and Biophysical Research Communications, 1999
The reactive metabolite(s) responsible for the expression of benzene toxicity is not clearly know... more The reactive metabolite(s) responsible for the expression of benzene toxicity is not clearly known despite extensive information on the metabolism and hematotoxicity of benzene. It is now widely believed that hematotoxicity of benzene is due to the concerted action of several metabolites which arise from multiple pathways of benzene. In our earlier study, we proposed iron polyphenol chelates as possible toxic metabolites of benzene due to their prooxidant activity. In continuation, we demonstrate the formation of an iron and 1,2,4-benzenetriol (BT) complex, when added together in an acetate buffer, 0.1 M, pH 5.6, by sephadex G-10 column chromatography. It was also observed that iron released from ferritin in the presence of BT formed a complex with BT.
Mutation Research-fundamental and Molecular Mechanisms of Mutagenesis, 2007
We have used V79MZ hamster lung fibroblasts stably transfected with human cytochrome P450-1A1 (hC... more We have used V79MZ hamster lung fibroblasts stably transfected with human cytochrome P450-1A1 (hCYP1A1; cell line designated V79MZh1A1) or P450-1B1 (hCYP1B1; cell line designated V79MZh1B1) alone, or in combination with human glutathione-S-transferase (GST) alpha-1 (hGSTA1), in order to examine GST protection against cytotoxicity and mutagenicity of dibenzo[a,l]pyrene (DBP) and the intermediate dihydrodiol metabolite (±)-DBP-11,12-dihydrodiol (DBPD). At comparable expression levels of hCYP1A1 and hCYP1B1, both DBP and DBPD were more cytotoxic in V79MZ1A1 (IC50 = 2.7 and 0.7 nM, respectively) than in V79MZh1B1 (IC50 = 6.0 and 4.8 nM, respectively). In contrast, both DBP and DBPD were two- to four-fold more mutagenic in V79MZh1B1 than in V79MZ1A1. Co-expression of hGSTA1 with hCYP1A1 decreased DBP cytotoxicity two-fold compared to V79MZh1A1 with hCYP1A1 alone, and provided a small, yet still statistically significant, 1.3-fold protection against DBPD. Protection against mutagenicity of these compounds was comparable to that for cytotoxicity in cells expressing hCYP1A1. In V79MZh1B1 cells, co-expression of hGSTA1 conferred up to five-fold protection against DBP cytotoxicity, and up to nine-fold protection against the (±)-DBP-dihydrodiol cytotoxicity relative to the cells expressing hCYP1B1 alone. Co-expression of hGSTA1 also reduced mutagenicity of DBP or its dihydrodiol to a lesser extent (1.3–1.8-fold) than the protection against cytotoxicity in cells expressing hCYP1B1. These findings demonstrate that the protective efficacy of hGSTA1 against DBP and DBPD toxicity is variable, depending on the compound or metabolite present, the specific cytochrome P450 isozyme expressed, and the specific cellular damage endpoint examined.
Toxicology, 2000
Glutathionyl hydroquinone (GHQ), a highly reactive metabolite of benzene, has been implicated as ... more Glutathionyl hydroquinone (GHQ), a highly reactive metabolite of benzene, has been implicated as a causative intermediate of benzene toxicity. To substantiate, the bioreactivity of GHQ was investigated under in vitro and in vivo conditions using end points, characteristic of benzene toxicity. Under in vitro conditions, the presence of GHQ: (a) linearly increased the release of aldehydic products from l-glutamate or deoxyuridine at GHQ concentrations of 5–25 μM and from rat liver homogenates at GHQ concentrations of 50–250 μM; (b) cleaved plasmid pUC 18 supercoiled DNA through a single strand nick to yield open circular relaxed DNA, and through a double strand cut to give out linear DNA at GHQ concentrations of 25–200 μM, with evidence of protection by catalase and superoxide dismutase; and (c) induced cross-linking and polymerization of lymphocyte nuclear DNA through in situ generation of GHQ, which was protected by pretreatment of lymphocytes with N-ethylmaleimide. In vivo exposure of Swiss albino mice to GHQ (100 mg/kg, intraperitoneally once daily for 30 days) resulted in significant increase of liver weight and inhibition of mitotic index in the bone marrow. The other test parameters, namely spleen weight, hematological indices, hepatic sulphahydryl content and nonenzymatic lipid peroxidation, and chromosomal aberrations in the bone marrow were, however, unaffected by GHQ treatment. The observations indicate pro-oxidant and cytotoxic potential of GHQ, mediated by the reactive oxygen species generated during the course of its auto-oxidation. Bioreactivity of GHQ with cellular macromolecules in vitro and inhibition of mitotic index of bone marrow on in vivo exposure have relevance to benzene toxicity, although in situ generation of GHQ at the site of action appears critical in bringing about hematological and chromosomal effects that were probably spared due to rapid metabolic disposition and, consequently, poor bioavailability of intraperitoneally administered GHQ.
Kidney International, 2005
Background. The activity of the organic anion transporter 1 (OAT1) has been implicated recently i... more Background. The activity of the organic anion transporter 1 (OAT1) has been implicated recently in the basolateral uptake of thiol conjugates of inorganic mercury in renal proximal tubular cells. However, very little is known about the role of OAT1 in the renal epithelial transport of organic forms of mercury, such as methylmercury (CH 3 Hg + ), especially when it is in the form of the cysteine (Cys) S-conjugate of methylmercury (CH 3 Hg-Cys), which is believed to be a biologically relevant form of mercury.
Toxicology Letters, 2002
Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human l... more Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human liver ferritin (HLF) with or without the presence of ascorbic acid. With ascorbic acid the rate of iron release from HLF by DMA(V) was intermediate (3.37 nM/min, P<0.05) and by DMA(III) was much higher (16.3 nM/min, P<0.001). No pBR322 plasmid DNA damage was observed from in vitro exposure to arsenate (iAs(V)), arsenite (iAs(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)) or DMA(V) alone. DNA damage was observed following DMA(III) exposure; coexposure to DMA(III) and HLF caused more DNA damage; considerably higher amounts of DNA damage was caused by coexposure of DMA(III), HLF and ascorbic acid. Diethylenetriaminepentaacetic acid (an iron chelator), significantly inhibited DNA damage. Addition of catalase (which can increase Fe2+ concentrations) further increased the plasmid DNA damage. Iron-dependent DNA damage could be a mechanism of action of human arsenic carcinogenesis.
Toxicology and Applied Pharmacology, 2003
Cadmium (Cd) is an industrial and environmental pollutant that affects adversely a number of orga... more Cadmium (Cd) is an industrial and environmental pollutant that affects adversely a number of organs in humans and other mammals, including the kidneys, liver, lungs, pancreas, testis, and placenta. The liver and kidneys, which are the primary organs involved in the elimination of systemic Cd, are especially sensitive to the toxic effects of Cd. Because Cd ions possess a high affinity for sulfhydryl groups and thiolate anions, the cellular and molecular mechanisms involved in the handling and toxicity of Cd in target organs can be defined largely by the molecular interactions that occur between Cd ions and various sulfhydryl-containing molecules that are present in both the intracellular and extracellular compartments. A great deal of scientific data have been collected over the years to better define the toxic effects of Cd in the primary target organs. Notwithstanding all of the new developments made and information gathered, it is surprising that very little is known about the cellular and molecular mechanisms involved in the uptake, retention, and elimination of Cd in target epithelial cells. Therefore, the primary purpose of this review is to summarize and put into perspective some of the more salient current findings, assertions, and hypotheses pertaining to the transport and handling of Cd in the epithelial cells of target organs. Particular attention has been placed on the molecular mechanisms involved in the absorption, retention, and secretion of Cd in small intestinal enterocytes, hepatocytes, and tubular epithelial cells lining both proximal and distal portions of the nephron. The purpose of this review is not only to provide a summary of published findings but also to provide speculations and testable hypotheses based on contemporary findings made in other areas of research, with the hope that they may promote and serve as the impetus for future investigations designed to define more precisely the cellular mechanisms involved in the transport and handling of Cd within the body.
Toxicology Letters, 2003
Many modes of action for arsenic carcinogenesis have been proposed, but few theories have a subst... more Many modes of action for arsenic carcinogenesis have been proposed, but few theories have a substantial mass of supporting data. Three stronger theories of arsenic carcinogenesis are production of chromosomal abnormalities, promotion of carcinogenesis and oxidative stress. This article presents the oxidative stress theory along with some supporting experimental data. In the area of which arsenic species is causually active, recent data have suggested that trivalent methylated arsenic metabolites, particularly monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III)), have a great deal of biological activity. Some evidence now indicates that these trivalent, methylated, and relatively less ionizable arsenic metabolites may be unusually capable of interacting with cellular targets such as proteins and even DNA. Thus for inorganic arsenic, oxidative methylation followed by reduction to trivalency may be a activation, rather than a detoxification pathway. This would be particularly true for arsenate. In forming toxic and carcinogenic arsenic species, reduction from the pentavalent state to the trivalent state may be as or more important than methylation of arsenic.
Toxicology, 1994
Bleomycin-dependent degradation of DNA in bone marrow cells was studied in vitro in the presence ... more Bleomycin-dependent degradation of DNA in bone marrow cells was studied in vitro in the presence of iron or iron polyphenol chelates which are formed during biotransformation of benzene. Iron polyphenol chelates markedly enhanced bleomycin-dependent DNA degradation in comparison to iron alone. About 1.5 and 2.5-fold increase was observed in the presence of iron hydroquinone (HQ) chelate and iron 1,2,4-benzenetriol (BT) chelate, respectively. Endogenous iron chelators such as glutamate, citrate, aspartate, glycine, cysteine, dithiothreitol, AMP, ADP and ATP did not enhance iron-catalysed bleomycin-dependent degradation of DNA. By bleomycin assay, the recovery of iron polyphenol chelate added externally to bone marrow lysate was complete. However, the presence of iron polyphenol chelate resulted in less thiobarbituric acid reactive products from glutamate or brain homogenate than with iron alone. The optical spectra of BT were modified in the presence of ferrous sulphate, revealing a new absorption peak at 259 nm indicating complexation with iron. Thus, the iron polyphenol chelate, on one hand, is a more potent DNA cleaving agent in the presence of bleomycin, and on the other hand, it is a less effective free radical generator as compared to iron alone.
Advances in Pharmacology, 2010
The contribution of the renin angiotensin system to physiology and pathology is undergoing a rapi... more The contribution of the renin angiotensin system to physiology and pathology is undergoing a rapid reconsideration of its mechanisms from emerging new concepts implicating angiotensin-converting enzyme 2 and angiotensin-(1-7) as new elements negatively influencing the vasoconstrictor, trophic, and pro-inflammatory actions of angiotensin II. This component of the system acts to oppose the vasoconstrictor and proliferative effects on angiotensin II through signaling mechanisms mediated by the mas receptor. In addition, a reduced expression of the vasodepressor axis composed by angiotensin-converting enzyme 2 and angiotensin-(1-7) may contribute to the expression of essential hypertension, the remodeling of heart and renal function associated with this disease, and even the physiology of pregnancy and the development of eclampsia.
Toxicology Letters, 2002
Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human l... more Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human liver ferritin (HLF) with or without the presence of ascorbic acid. With ascorbic acid the rate of iron release from HLF by DMA(V) was intermediate (3.37 nM/min, PB 0.05) and by DMA(III) was much higher (16.3 nM/min, P B 0.001). No pBR322 plasmid DNA damage was observed from in vitro exposure to arsenate (iAs(V)), arsenite (iAs(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)) or DMA(V) alone. DNA damage was observed following DMA(III) exposure; coexposure to DMA(III) and HLF caused more DNA damage; considerably higher amounts of DNA damage was caused by coexposure of DMA(III), HLF and ascorbic acid. Diethylenetriaminepentaacetic acid (an iron chelator), significantly inhibited DNA damage. Addition of catalase (which can increase Fe 2 + concentrations) further increased the plasmid DNA damage. Iron-dependent DNA damage could be a mechanism of action of human arsenic carcinogenesis.
Toxicology and Applied Pharmacology, 2003
Cadmium (Cd) is an industrial and environmental pollutant that affects adversely a number of orga... more Cadmium (Cd) is an industrial and environmental pollutant that affects adversely a number of organs in humans and other mammals, including the kidneys, liver, lungs, pancreas, testis, and placenta. The liver and kidneys, which are the primary organs involved in the elimination of systemic Cd, are especially sensitive to the toxic effects of Cd. Because Cd ions possess a high affinity for sulfhydryl groups and thiolate anions, the cellular and molecular mechanisms involved in the handling and toxicity of Cd in target organs can be defined largely by the molecular interactions that occur between Cd ions and various sulfhydryl-containing molecules that are present in both the intracellular and extracellular compartments. A great deal of scientific data have been collected over the years to better define the toxic effects of Cd in the primary target organs. Notwithstanding all of the new developments made and information gathered, it is surprising that very little is known about the cellular and molecular mechanisms involved in the uptake, retention, and elimination of Cd in target epithelial cells. Therefore, the primary purpose of this review is to summarize and put into perspective some of the more salient current findings, assertions, and hypotheses pertaining to the transport and handling of Cd in the epithelial cells of target organs. Particular attention has been placed on the molecular mechanisms involved in the absorption, retention, and secretion of Cd in small intestinal enterocytes, hepatocytes, and tubular epithelial cells lining both proximal and distal portions of the nephron. The purpose of this review is not only to provide a summary of published findings but also to provide speculations and testable hypotheses based on contemporary findings made in other areas of research, with the hope that they may promote and serve as the impetus for future investigations designed to define more precisely the cellular mechanisms involved in the transport and handling of Cd within the body.
Toxicology, 2000
Glutathionyl hydroquinone (GHQ), a highly reactive metabolite of benzene, has been implicated as ... more Glutathionyl hydroquinone (GHQ), a highly reactive metabolite of benzene, has been implicated as a causative intermediate of benzene toxicity. To substantiate, the bioreactivity of GHQ was investigated under in vitro and in vivo conditions using end points, characteristic of benzene toxicity. Under in vitro conditions, the presence of GHQ: (a) linearly increased the release of aldehydic products from L-glutamate or deoxyuridine at GHQ concentrations of 5-25 mM and from rat liver homogenates at GHQ concentrations of 50 -250 mM; (b) cleaved plasmid pUC 18 supercoiled DNA through a single strand nick to yield open circular relaxed DNA, and through a double strand cut to give out linear DNA at GHQ concentrations of 25 -200 mM, with evidence of protection by catalase and superoxide dismutase; and (c) induced cross-linking and polymerization of lymphocyte nuclear DNA through in situ generation of GHQ, which was protected by pretreatment of lymphocytes with N-ethylmaleimide. In vivo exposure of Swiss albino mice to GHQ (100 mg/kg, intraperitoneally once daily for 30 days) resulted in significant increase of liver weight and inhibition of mitotic index in the bone marrow. The other test parameters, namely spleen weight, hematological indices, hepatic sulphahydryl content and nonenzymatic lipid peroxidation, and chromosomal aberrations in the bone marrow were, however, unaffected by GHQ treatment. The observations indicate pro-oxidant and cytotoxic potential of GHQ, mediated by the reactive oxygen species generated during the course of its auto-oxidation. Bioreactivity of GHQ with cellular macromolecules in vitro and inhibition of mitotic index of bone marrow on in vivo exposure have relevance to benzene toxicity, although in situ generation of GHQ at the site of action appears critical in bringing about hematological and chromosomal effects that were probably spared due to rapid metabolic disposition and, consequently, poor bioavailability of intraperitoneally administered GHQ.
PLoS ONE, 2011
Background: Angiotensin-(1-12) ] functions as an endogenous substrate for the productions of Ang ... more Background: Angiotensin-(1-12) ] functions as an endogenous substrate for the productions of Ang II and Ang-(1-7) by a non-renin dependent mechanism. This study evaluated whether Ang-(1-12) is incorporated by neonatal cardiac myocytes and the enzymatic pathways of 125 I-Ang-(1-12) metabolism in the cardiac myocyte medium from WKY and SHR rats.
PLoS ONE, 2013
The cardioprotective effects of estrogen are well recognized, but the mechanisms remain poorly un... more The cardioprotective effects of estrogen are well recognized, but the mechanisms remain poorly understood. Accumulating evidence suggests that the local cardiac renin-angiotensin system (RAS) is involved in the development and progression of cardiac hypertrophy, remodeling, and heart failure. Estrogen attenuates the effects of an activated circulating RAS; however, its role in regulating the cardiac RAS is unclear. Bilateral oophorectomy (OVX; n = 17) or sham-operation (Sham; n = 13) was performed in 4-week-old, female mRen2.Lewis rats. At 11 weeks of age, the rats were randomized and received either 17 bestradiol (E2, 36 mg/pellet, 60-day release, n = 8) or vehicle (OVX-V, n = 9) for 4 weeks. The rats were sacrificed, and blood and hearts were used to determine protein and/or gene expression of circulating and tissue RAS components. E2 treatment minimized the rise in circulating angiotensin (Ang) II and aldosterone produced by loss of ovarian estrogens. Chronic E2 also attenuated OVX-associated increases in cardiac Ang II, Ang-(1-7) content, chymase gene expression, and mast cell number. Neither OVX nor OVX+E2 altered cardiac expression or activity of renin, angiotensinogen, angiotensin-converting enzyme (ACE), and Ang II type 1 receptor (AT1R). E2 treatment in OVX rats significantly decreased gene expression of MMP-9, ACE2, and Ang-(1-7) mas receptor, in comparison to sham-operated and OVX littermates. E2 treatment appears to inhibit upsurges in cardiac Ang II expression in the OVX-mRen2 rat, possibly by reducing chymase-dependent Ang II formation. Further studies are warranted to determine whether an E2-mediated reduction in cardiac chymase directly contributes to this response in OVX rats. Citation: Wang H, Jessup JA, Zhao Z, Da Silva J, Lin M, et al. (2013) Characterization of the Cardiac Renin Angiotensin System in Oophorectomized and Estrogen-Replete mRen2.Lewis Rats. PLoS ONE 8(10): e76992.