Impaired flow-induced dilation in mesenteric resistance arteries from receptor protein tyrosine phosphatase-μ-deficient mice (original) (raw)
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British Journal of Pharmacology, 2000
In resistance arteries pressure-induced (myogenic) tone (MT) and flow (shear stress)-induced dilation (FD) are potent determinant of vascular resistance. We investigated the role of angiotensin II and endothelin-1 in FD and MT in resistance arteries and their potential change in hypertension. Flow - diameter - pressure relationship was established in situ, under anaesthesia, in two daughter branches of a mesenteric resistance artery (180 microM, n=7 per group) from spontaneously hypertensive (SHR) or normotensive (WKY) rats. One artery was ligated distally, so that it was submitted to pressure only, while the other was submitted to pressure and flow. Drugs were added to the preparation and external diameter, pressure and flow measured continuously. External diameter (with flow) ranged from 150+/-3 to 191+/-7 microM in WKY (n=28) rats and from 168+/-6 to 186+/-6 microM in SHR (n=28). Flow induced a dilation of the non-ligated arteries which was lower in SHR (13+/-5 - 31+/-4 microM vs WKY: 5+/-5 - 44+/-4 microM). In the ligated artery, the diameter did not significantly change, due to MT. In the vessels submitted to flow angiotensin converting enzyme inhibition (perindopril, 10 micromol L(-1)) increased the diameter in SHR (+11+/-2 microM) significantly more than in WKY (+2+/-1 microM). Angiotensin type 1 receptor (AT(1)R) blockade (losartan, 10 micromol L(-1)) increased the diameter in the vessels with flow in SHR only (+6+/-1 microM). Angiotensin type 2 receptor (AT(2)R) blockade (PD 123319, 1 micromol L(-1)) decreased arterial diameter in WKY only (9+/-2). Endothelin-1 type A receptor (ET(A)R) blockade (LU135252, 0.1 micromol L(-1)) increased the diameter only in SHR in the artery submitted to flow (by 6+/-1 microM). Thus FD was counteracted by a flow-dependent AT(1) and ET(A) receptors-activation in SHR whereas in WKY FD AT(2)-dependent dilation is involved.
Experimental Cell Research, 1999
We investigated the localization of receptor-type protein-tyrosine phosphatase (RPTP) in tissues by immunofluorescence. RPTP immunoreactivity was found almost exclusively within vascular endothelial cells. RPTP was more abundant in the arterial tree than in the venous circulation. This pattern of expression was opposite to that of the von Willebrand factor and demonstrated a lack of difference in expression of VE-cadherin. RPTP was undetectable in the endocardium. In agreement with previous work on nonendothelial cell lines, RPTP was exclusively at the lateral aspects of endothelial cells in vivo and at cell-cell contacts as well as ex vivo in two-or three-dimensional endothelial cell cultures, and expression levels were upregulated by cell density. RPTP was detected in few other cells: bronchial and biliary epithelia and cardiocytes (intercalated discs). Our results identify RPTP as a new marker of endothelial cell heterogeneity and suggest a possible role in endothelial-specific functions, involving cell-cell contact.
Vascular Pharmacology, 2016
Chronic kidney disease (CKD) and hypertension are co-morbid conditions both associated with altered resistance artery structure, biomechanics and function. We examined these characteristics in mesenteric artery together with renal function and systolic blood pressure (SBP) changes in the Lewis polycystic kidney (LPK) rat model of CKD. Animals were studied at early (6-weeks), intermediate (12-weeks), and late (18-weeks) time-points (n = 21), relative to age-matched Lewis controls (n = 29). At 12 and 18-weeks, LPK arteries exhibited eutrophic and hypertrophic inward remodelling characterised by thickened medial smooth muscle, decreased lumen diameter, and unchanged or increased media cross-sectional area, respectively. At these later time points, endothelium-dependent vasorelaxation was also compromised, associated with impaired endotheliumdependent hyperpolarisation and reduced nitric oxide synthase activity. Stiffness, elastic-modulus/stress slopes and collagen/elastin ratios were increased in 6 and 18-week-old-LPK, in contrast to greater arterial compliance at 12 weeks. Multiple linear regression analysis highlighted SBP as the main predictor of wall-lumen ratio (r = 0.536, P b 0.001 n = 46 pairs). Concentration-response curves revealed increased sensitivity to phenylephrine but not potassium chloride in 18-week-LPK. Our results indicate that impairment in LPK resistance vasculature is evident at 6 weeks, and worsens with hypertension and progression of renal disease.
Flow-induced arterial remodeling in rat mesenteric vasculature
This study was designed to characterize in vivo arterial remodeling of male Wistar rat small mesenteric arteries exposed to varying levels of elevated blood flow in the presence of normal arterial pressure. Through a series of arterial ligations, respective ileal artery and second-order branch blood flows acutely increased ϳ36 and ϳ170% over basal levels. Their respective diameters increased 12 and 38% and their wall area increased 58 and 120% in a timedependent fashion between 1 and 7 days postligation compared with same-animal control vessels. Medial extracellular connective tissue increased concomitantly with medial wall hypertrophy. Immunostaining for proliferating cell nuclear antigen and nuclear profile analyses suggests that both smooth muscle and endothelial cell hyperplasia contribute to flow-induced vascular remodeling. The initial stimulus in this model is flow-mediated shear stress, with possible augmentation by hoop stress, which is increased ϳ7% by the resultant vasodilation. Stable wall thickness-to-lumen diameter ratios at 1, 3, and 7 days, however, suggest chronic hoop stress is tightly regulated and remains constant. The model described herein allows analyses of two arteries with different degrees of flow elevation within the same animal and demonstrates that the magnitude of vessel remodeling in vivo is directly dependent on the duration of flow elevation after abrupt arterial occlusion. shear stress; mesenteric arteries; medial wall hypertrophy; cellular hyperplasia
AJP: Heart and Circulatory Physiology, 2008
Resistance arteries are the site of the earliest manifestations of many cardiovascular and metabolic diseases. Flow (shear stress) is the main physiological stimulus for the endothelium through the activation of vasodilatory pathways generating flowmediated dilation (FMD). The role of FMD in local blood flow control and angiogenesis is well established and alterations in FMD are early markers of cardiovascular disorders. The alpha-1 integrin, which has a role in angiogenesis, could be involved in FMD. FMD was studied in mesenteric resistance arteries (MRA) isolated in arteriographs. The role of alpha-1 integrins in FMD was tested using selective antibodies and mice lacking the gene encoding for alpha-1 integrins. Both anti alpha-1 blocking antibodies and genetic deficiency in alpha-1-integrin in mice (alpha-1 -/-) inhibited FMD without affecting receptor-mediated (acetylcholine) endothelium-dependent dilation or endothelium independent dilation (sodium nitroprusside). Similarly, vasoconstrictor tone (myogenic tone and phenylephrineinduced contraction) was not affected. In MRA phosphorylated-Akt and PI3-kinase were significantly lower in alpha-1 -/mice than in alpha-1 +/+ mice, although total Akt and eNOS were not affected. Pharmacological blockade of PI3kinase-Akt pathway with LY294002 inhibited FMD. This inhibitory effect of LY294002 was significantly lower in alpha-1 -/mice than in alpha-1 +/+ mice. Thus, alpha-1 integrin has a key role in flow (shear stress)-dependent vasodilation in resistance arteries by transmitting the signal to eNOS through activation of PI3kinase and Akt. Due to the central role of flow (shear stress) activation of the endothelium in vascular disorders this finding opens new perspectives in the pathophysiology of the microcirculation and provides new therapeutic targets.
The International journal of developmental biology, 2003
The receptor-like protein tyrosine phosphatase mu (RPTPmu) belongs to the subfamily of meprin, A5, RPTPmu (MAM) domain-containing RPTPs, which are thought to play an important role in cell-cell adhesion mediated processes. The current study was designed to examine the expression pattern of RPTPmu in mice. We have generated RPTPmu-LacZ knock-in mice that express the beta-galactosidase (LacZ) reporter gene under the control of the RPTPmu promoter. LacZ expression patterns were analysed in embryos and adult mice by whole mount LacZ staining. Analysis of beta-galactosidase activity of heterozygous embryos and adult tissues revealed RPTPmu expression in endothelial cells of arteries and capillaries. In contrast, expression was virtually absent in endothelial cells of veins and in fenestrated endothelial cells in the adult liver and spleen. Moreover, RPTPmu expression was found in endothelial cells from the endocardium and the aorta in embryos, but not in adult mice. In addition to hetero...
British Journal of Pharmacology, 1997
1 We have studied the eect of endothelin-1 stimulation on protein tyrosine phosphorylation levels in intact small mesenteric arteries of the rat and investigated the eects of tyrosine kinase inhibition on the contractile response to this agonist. 2 Endothelin-1 stimulated a rapid (20 s), sustained (up to 20 min) and concentration-dependent (1 ± 100 nM) increase in protein tyrosine phosphorylation levels which coincided temporally with the contractile response in intact and a-toxin permeabilized small artery preparations. Tyrosine phosphorylation was increased in four main clusters of proteins of apparent molecular mass 28 ± 33, 56 ± 61, 75 ± 85 and 105 ± 115 kDa. Endothelin-1-induced protein tyrosine phosphorylation was independent of extracellular calcium, antagonized by the tyrosine kinase inhibitor tyrphostin A23 but not by the inactive tyrphostin A1.
Regulation of endothelial barrier function during flow-induced conversion to an arterial phenotype
Cardiovascular Research, 2007
Objective: Flow-induced conversion of endothelial cells into an elongated arterial phenotype requires a coordinated regulation of cell junctions. Here we investigated the effect of acute and chronic flow on junction regulation. Methods and results: Using an extended experimental setup that allows analyses of endothelial barrier function under flow conditions, we found a flow-induced upregulation of the transendothelial electrical resistance within minutes. This was accompanied by an increase in actin filaments along the junctions and vascular endothelial (VE)-cadherin clustering, which was identified at nanoscale resolution by stimulated emission depletion microscopy. In addition, a transient tyrosine phosphorylation of VE-cadherin and catenins occurred within minutes following the onset of flow. VE-cadherin and actin distribution were maintained under chronic flow over 24 h and associated with the upregulation of VE-cadherin and α-catenin expression, thus compensating for the cell elongation-mediated increase in cell border length. Importantly, all observed effects were rac1 dependent as verified by the inhibitory effect of dominant negative N17rac1. Conclusion: These results show that flow-induced conversion of endothelial cells into an arterial phenotype occurs while intercellular junctions remain intact. The data place rac1 in a central multimodal regulatory position that might be important in the development of vascular diseases, such as arteriosclerosis.
Clinical and Experimental Pharmacology and Physiology, 2002
1. An increase in transmural pressure in arterioles results in a shortening of vascular smooth muscle cells, with subsequent constriction of the vessel. The mechanisms underlying this myogenic contraction are not fully understood; however, the obligatory role of increases in intracellular [Ca 2؉ ] and myosin light chain phosphorylation have been demonstrated. 2. The myogenic response shows a relationship with smooth muscle cell membrane potential and influx of extracellular Ca 2؉ through voltage-operated Ca 2؉ channels (VOCC). Mechanically sensitive channels and possibly release of Ca 2؉ from intracellular stores may play a role. However, there are other components of myogenic contraction that cannot be explained by a Ca 2؉-MLCK mechanism, for example the initial sensing of alterations in transmural pressure, whether sustained myogenic constriction involves myofilament Ca 2؉ sensitization or remodelling of the vessel wall in response to a maintained increase in transmural pressure. 3. In an attempt to investigate these areas, recent studies have examined a role for tyrosine phosphorylation pathways in pressure-induced contraction of arterioles. In rat pressurized cremaster arterioles, tyrosine kinase inhibitors dilated vessels showing spontaneous myogenic tone and tyrosine phosphatase inhibitors caused vasoconstriction. However, pressure-induced myogenic constriction of vessels persisted in the presence of these agents. Biochemical studies revealed that phosphotyrosine formed at a relatively slow rate (significant after 5 min, with maximal increase after approximately 15 min) in response to increased vessel transmural pressure, in contrast with myosin light chain phosphorylation or the time-course of myogenic constriction itself (maximum within 1 min). 4. Taken together, these observations support the idea of a role for tyrosine phosphorylation pathways in longer-term responses to increased transmural pressure rather than acute myogenic constriction. Phosphotyrosine formation was also more closely correlated to vessel wall tension (pressure ؋ diameter) than the diameter of the arterioles alone. The identity of the tyrosine-phosphorylated proteins requires further investigation; however, there is some evidence supporting roles for cSrc-type tyrosine kinases and p44 mitogen-activated protein kinase. The longer-term responses of blood vessels to increased transmural pressure that may involve tyrosine phosphorylation pathways include maintenance of myogenic constriction and vessel wall remodelling. Key words: arterioles, Ca 2؉ signalling, myogenic response, myosin light chain kinase, tyrosine phosphorylation, vascular smooth muscle. INTRACELLULAR [Ca 2+ ] AND MYOSIN LIGHT CHAIN PHOSPHORYLATION Myogenic constriction is heavily dependent on smooth muscle intracellular [Ca 2+ ]. 5-9 Increases in vessel transmural pressure are