Activities of Some Caspase Cascade Enzymes and Myocardial Contractility in Experimental Left Ventricular Focal Ischemia (original) (raw)
Related papers
Induction of Caspase Cascade as a Nonspecific Response to Myocardial Damage
Bulletin of Experimental Biology and Medicine, 2011
In three experimental series, acute hemodynamic overload of the left ventricle, focal ischemia of the left ventricle, and diphtheritic intoxication were modeled in rabbits. On days 1, 3, and 5 of the experiments, activity of myocardial caspase-3 and caspase-8 were measured separately in the left and right ventricles. In the left ventricle, caspase-3 activity increased in all 3 modeled pathological processes, while in the right ventricle this parameter increased during acute overload and ischemic injury to the left ventricle. Caspase-8 activity increased only in the left ventricle during its hemodynamic overload and remained unchanged in other cases. It was concluded that induction of the caspase cascade can be considered as a nonspecific response to myocardial damage. In this case, specifi c mechanisms responsible for generation and transmission of apoptotic stimuli in cardiomyocytes have unique features.
Biochemistry (Moscow) Supplement Series B: Biomedical Chemistry, 2011
It is well known that chronic overload of the cardiac left ventricle is accompanied by an increase in the cardiomyocyte apoptosis rate. However, direction and extent of changes in programmed cell death under an acute overload of the left ventricle still requires detailed investigation (as its pathogenesis significantly differs from chronic overload). Caspase-3 activity has been investigated in left ventricle myocardium of rabbits on days 1, 3, and 5 after modeling of left ventricle hemodynamic overload caused by experimental stenosis of the ascending aorta. Control group included intact animals. It was found that caspase-3 activity significantly increased in both ventricles on day 1; it increased more than twofold above control values on day 3 and decreased up to nearly control values on day 5. Based on these data it was concluded that the acute hemodynamic overload of the left ventricle may be a cause of increased apoptosis in the myocardial tissue of both cardiac ventricles during first days of the pathological process.
Journal of Molecular and Cellular Cardiology, 2001
33, 983-994. Interpretation of the rate of apoptosis in diseased hearts is hampered by the fact that the time course of the apoptotic cascade in adult cardiomyocytes is largely unknown. Therefore, we established a standardized in vitro system, relevant to the in vivo situation of heart failure, using adult de-and redifferentiating cardiomyocytes to determine the time intervals necessary for the different steps of the apoptotic cascade to occur. Apoptosis was induced with 0.1 mmol/l H 2 O 2 in adult rat cardiomyocytes 10 days in culture. Dosages >0.5 mmol/ l H 2 O 2 produced necrosis. Disruption of the mitochondrial membrane potential ( m) was the earliest sign of apoptosis and occurred at 2 h after H 2 O 2 exposure. The number of annexin V (translocation of phosphatidylserine) and PhiPhiLux (activation of caspase-3) positive cells significantly increased after 4 h and remained constant thereafter. Bcl-2 levels decreased. At 9 h, Bax expression was significantly elevated resulting in a reduced Bcl-2/ Bax ratio. DNA fragmentation detected by TUNEL and ssDNA peaked at 14 h, parallel to the appearance of apoptotic ultrastructural changes. Although DNA fragmentation was inhibited by zVAD-fmk, Ac-DEVD-CHO, zLEVD-fmk, these caspase inhibitors failed to inhibit disruption of m and increased the number of necrotic cells. Catalase inhibited both apoptosis and necrosis. Our results indicate that the occurrence of the different steps of the apoptotic cascade is time-dependent and tightly regulated. Caspase inhibitors reduce apoptosis but increase the rate of necrosis, suggesting that the cells are destined to die upstream of the caspase step, i.e. by mitochondrial damage. These data provide the basis for the critical evaluation and interpretation of the occurrence of apoptosis in failing hearts.
BMC physiology, 2005
The importance of apoptosis in the injury sustained by the human myocardium during ischaemia and reoxygenation and the underlying mechanisms remain unclear. To quantify apoptosis and necrosis induced by simulated ischaemia/reoxygenation in the human atrial myocardium, free-hand sections of right atrial appendage (n = 8/group) were subjected to 90 minutes simulated ischaemia followed by 2, 8 and 24 hours reoxygenation. Apoptosis, as assessed by TUNEL, was greater than necrosis after 90 minutes simulated ischaemia and 2 hours reoxygenation (35.32 +/- 3.22% vs 13.55 +/- 1.3%; p < 0.05) but necrosis was greater than apoptosis by 24 hours reoxygenation (45.20 +/- 2.75% vs 4.82 +/- 0.79%; p < 0.05). Total caspase activation was similar after 90 minutes simulated ischaemia followed by 2 hours and 24 hours reoxygenation (515270 +/- 99570 U vs 542940 +/- 95216 U; p = NS). However, caspase-3 like activation was higher at 2 hours than at 24 hours reoxygenation (135900 +/- 42200 U vs 5497...
Caspase Inhibition Reduces Myocyte Cell Death Induced by Myocardial Ischemia and Reperfusion In Vivo
Journal of Molecular and Cellular Cardiology, 1999
Myocardial ischemia and reperfusion lead to myocyte cell death, at least in part, by an apoptotic mechanism. Caspases are a conserved family of proteases that play an essential role in the execution of apoptosis; however, their potential contribution to ischemic myocardial cell death is largely unknown. To examine their role in this process, we subjected rabbits to 30 min of coronary artery occlusion followed by 3 h of reperfusion. Immunoblot analyses revealed that caspases-2, -3 and -7 were proteolytically activated during myocardial ischemia and reperfusion in vivo. In addition, the well-characterized caspase substrate poly(ADP-ribose) polymerase (PARP) was selectively cleaved into its signature apoptotic fragment in ischemic/reperfused myocardium. Systemic administration of the broad-spectrum caspase inhibitor acetyl-Tyr-Val-Ala-Asp chloromethylketone (YVAD-cmk, 4.8 mg/kg) partially blocked caspase activation and dramatically reduced the percentage of terminal dUTP deoyxynucleotidyl-transferase nick end-labeling (TUNEL)-positive myocyte nuclei in the infarct region (3.9±0.8% v 13.0±2.2% in control animals, P=0.012). Moreover, YVADcmk reduced myocardial infarct size by approximately 31% (31.1±3.3% v 45.3±4.9% in control animals, P= 0.032). These results indicate that caspases are critical mediators of myocardial injury induced by ischemia and reperfusion in vivo, and they suggest that caspase inhibition may be therapeutically beneficial in myocardial infarction.
Activation of caspase-3 may not contribute to postresuscitation myocardial dysfunction
AJP: Heart and Circulatory Physiology, 2009
We have previously reported that postresuscitation myocardial dysfunction is accompanied by the release of cytochrome c and caspase-3 activation. We now investigated the role of caspase-3 activation by examining whether such process prompts apoptotic DNA fragmentation, whether caspase-3 inhibition attenuates myocardial dysfunction, and whether myocardial protective effects of sodium-hydrogen exchanger isoform-1 (NHE-1) inhibition involve caspase-3 inhibition using a rat model of ventricular fibrillation (VF) of closed-chest resuscitation. Resuscitation after 4 or 8 min of untreated VF caused significant reductions in left ventricular stroke work index averaging 23% of sham control rats at 4 h postresuscitation. Left ventricular dysfunction was accompanied by increases in cytosolic cytochrome c, decreases in pro- and cleaved caspase-9 fragments, increases in 17-kDa caspase-3 fragments, and increases in caspase-3 activity indicating the activation of the mitochondrial apoptotic pathwa...
Ventricular Myocyte Caspases Are Directly Responsible for Endotoxin-Induced Cardiac Dysfunction
Circulation, 2005
Background-Although most of the deleterious effects of sepsis-induced apoptosis have been attributed to increased lymphocyte cell death, caspase activation may directly alter cell function of different organ systems. We postulated that left ventricular (LV) cardiomyocyte caspase activation is directly involved in sepsis-induced heart contractile dysfunction. Methods and Results-LV cardiomyocytes isolated 4 hours after rat treatment with endotoxin injection (10 mg/kg) displayed major reductions in contractile reserve and myofilament response to Ca 2ϩ . Concomitantly, endotoxin also induced increases in LV cardiomyocyte caspase-3, -8, and -9-like activities, which were associated with sarcomeric structure destruction and cleavage of components of the cardiac myofilament. Interestingly, zVAD.fmk treatment of septic rat prevented LV cardiomyocyte contractile dysfunction, reductions in myofilament response to calcium, troponin T cleavage, and sarcomere destruction. Serum (10%) of endotoxin-treated rats induced contractile dysfunction, caspase-3-like activity increase, and troponin T cleavage of naive LV cardiomyocytes. The effects of septic serum were prevented in LV cardiomyocytes isolated from zVAD.fmk-or zDEVD.cmk-treated rats or LV cardiomyocytes preincubated with zVAD.fmk or zDEVD.cmk.
Attenuation of Ischemia/Reperfusion Injury in Rats by a Caspase Inhibitor
Circulation, 1998
Background-Z-Val-Ala-Asp(OMe)-CH 2 F (ZVAD-fmk), a tripeptide inhibitor of the caspase interleukin-1-converting enzyme family of cysteine proteases, may reduce myocardial reperfusion injury in vivo by attenuating cardiomyocyte apoptosis within the ischemic area at risk. Methods and Results-Sprague-Dawley rats were subjected to a 30-minute coronary occlusion followed by a 24-hour