Polyphenol (-)-Epigallocatechin Gallate during Ischemia Limits Infarct Size Via Mitochondrial KATP Channel Activation in Isolated Rat Hearts

Abstract

Polyphenol (-)-epigallocatechin gallate (EGCG), the most abundant catechin of green tea, appears to attenuate myocardial ischemia/reperfusion injury. We investigated the involvement of ATP-sensitive potassium (KATP) channels in EGCG-induced cardioprotection. Isolated rat hearts were subjected to 30 min of regional ischemia and 2 hr of reperfusion. EGCG was perfused for 40 min, from 10 min before to the end of index ischemia. A nonselective KATP channel blocker glibenclamide (GLI) and a selective mitochondrial KATP (mKATP) channel blocker 5-hydroxydecanoate (HD) were perfused in EGCG-treated hearts. There were no differences in coronary flow and cardiodynamics including heart rate, left ventricular developed pressure, rate-pressure product, +dP/dtmax, and -dP/dtmin throughout the experiments among groups. EGCG-treatment significantly reduced myocardial infarction (14.5±2.5% in EGCG 1 mM and 4.0±1.7% in EGCG 10 mM, P<0.001 vs. control 27.2±1.4%). This antiinfarct effect was totally abrogated by 10 mM GLI (24.6±1.5%, P<0.001 vs. EGCG). Similarly, 100 mM HD also aborted the anti-infarct effect of EGCG (24.1±1.2%, P< 0.001 vs. EGCG ). These data support a role for the KATP channels in EGCG-induced cardioprotection. The mKATP channels play a crucial role in the cardioprotection by EGCG.