rottlerin and Hyperhomocysteinemia

The present study has been designed to investigate the possible role of protein kinase C-delta (PKC-delta) in hyperhomocysteinemia-induced attenuation of cardioprotective potential of ischemic preconditioning (IPC). Rats were administered L-methionine (1.7 g/kg/day, p.o.) for 4 weeks to produce hyperhomocysteinemia. Isolated Langendorff perfused normal and hyperhomocysteinemic rat hearts were subjected to global ischemia for 30 min followed by reperfusion for 120 min. Myocardial infarct size was assessed macroscopically using triphenyltetrazolium chloride (TTC) staining. Coronary effluent was analyzed for lactate dehydrogenase (LDH) and creatine kinase (CK) release to assess the degree of cardiac injury. Moreover, the oxidative stress in heart was assessed by measuring lipid peroxidation and superoxide anion generation. The ischemia-reperfusion (I/R) was noted to produce myocardial injury as assessed in terms of increase in myocardial infarct size, LDH and CK in coronary effluent and oxidative stress in normal and hyperhomocysteinemic rat hearts. In addition, the hyperhomocysteinemic rat hearts showed enhanced I/R-induced myocardial injury with high degree of oxidative stress as compared with normal rat hearts subjected to I/R. Four episodes of IPC (5 min each) afforded cardioprotection against I/R-induced myocardial injury in normal rat hearts as assessed in terms of reduction in myocardial infarct size, LDH, CK and oxidative stress. On the other hand, IPC mediated myocardial protection against I/R-injury was abolished in hyperhomocysteinemic rat hearts. Treatment with rottlerin (10 microM), a selective inhibitor of PKC-delta did not affect the cardioprotective effects of IPC in normal rat hearts; but its treatment significantly restored the cardioprotective potentials of IPC in hyperhomocysteinemic rat hearts. The high degree of oxidative stress produced in hyperhomocysteinemic rat hearts during reperfusion may activate PKC-delta, which may be implicated in the observed paradoxically abrogated cardioprotective potentials of IPC in hyperhomocysteinemic rat hearts.

Topics: Acetophenones; Animals; Benzopyrans; Enzyme Activation; Female; Hyperhomocysteinemia; Ischemic Preconditioning, Myocardial; Lipid Peroxidation; Male; Methionine; Myocardial Infarction; Oxidative Stress; Protein Kinase C-delta; Protein Kinase Inhibitors; Rats; Rats, Wistar; Reperfusion Injury; Superoxides

Recently we have demonstrated that the cardioprotective potential of ischemic postconditioning (IPOC) against ischemia and reperfusion (I/R)-induced myocardial injury was markedly suppressed in hyperhomocysteinemic (Hhcy) rat hearts. The present study investigated the possible role of PKC-delta in Hhcy-induced suppression of myocardial infarct size-limiting effect of IPOC.. Isolated Langendorff's perfused normal and Hhcy rat hearts were subjected to 30-min global ischemia (I), followed by 120-min reperfusion (R). The myocardial damage was assessed by measuring the infarct size, and analyzing the release of LDH and CK-MB in coronary effluent. The oxidative stress in the heart was assessed by measuring lipid peroxidation and superoxide anion generation.. The I/R produced myocardial injury in normal and Hhcy rat hearts by increasing myocardial infarct size, LDH and CK in coronary effluent and oxidative stress. Hhcy rat hearts exhibited enhanced I/R-induced myocardial injury and high oxidative stress as compared to normal rat hearts subjected to I/R. The IPOC (six brief episodes of I/R, 10s each) afforded cardioprotection against I/R-induced myocardial injury in normal rat hearts; but IPOC-mediated cardioprotection was abolished in Hhcy rat hearts. Treatment with rottlerin (10 microM), a selective inhibitor of PKC-delta, did not affect the cardioprotective effect of IPOC in normal rat hearts; but its treatment significantly restored the myocardial infarct size-limiting effect of IPOC in Hhcy rat hearts.. The high oxidative stress produced in Hhcy rat hearts during reperfusion may activate PKC-delta, which may be responsible for impairing the infarct size-limiting potential of IPOC in Hhcy rat hearts.

Topics: Acetophenones; Animals; Benzopyrans; Creatine Kinase, MB Form; Female; Hyperhomocysteinemia; In Vitro Techniques; Ischemic Preconditioning, Myocardial; L-Lactate Dehydrogenase; Lipid Peroxidation; Male; Myocardial Infarction; Myocardial Reperfusion Injury; Oxidative Stress; Protein Kinase C-delta; Rats; Rats, Wistar; Superoxides