Calcium activated potassium channel and protein kinase C participate in the cardiac protection of remote post conditioning

The present study was designed to investigate the roles of Ca2+ activated K+ channel (KCa) and protein kinase C (PKC) in the protective mechanisms of remote ischemic post conditioning (RPostC) when rat heart was subjected to ischemia/reperfusion (I/R) injury in vivo. Rat heart was subjected to regional ischemia for 45 min and reperfusion for 180 min in vivo to mimic I/R injury. RPostC was induced by 5 min right femoral artery occlusion followed by 5 min reperfusion for 3 cycles (totally 30 min) after 15 min of cardiac ischemia. Delayed remote ischemic post conditioning (delayed RPostC) was induced after 10 min of cardiac reperfusion. The hemodynamic parameters including mean arterial blood pressure and heart rate (HR) were recorded, and lactate dehydrogenase (LDH) release in plasma and infarct size were determined, and arrhythmia scores were calculated. In contrast to I/R, RPostC reduced infarct size and LDH release during reperfusion, the occurrence of arrhythmia was decreased, but no changes in delayed RPostC. The specific inhibitor of KCa iberiotoxin and PKC inhibitor chelerythrine both attenuated the role of RPostC. The findings indicated that RPostC had a protective effect on myocardial ischemia/reperfusion injury. Opening of KCa and activating of PKC may be involved in the mechanisms of RPostC.