Acute Alcohol-induced Protection against Infarction in Rabbit Hearts: Differences from and Similarities to Ischemic Preconditioning

Recent studies reveal that brief ethanol exposure induces cardioprotection against simulated ischemia in cardiomyocytes by the activation of protein kinase C- ε. The present study tests the ability of ethanol to induce protection in rabbit hearts in which infarct size was the end-point and explores the signal transduction pathways involved. In isolated rabbit hearts, 50 m ethanol infused for 5 min with 10 min of washout prior to 30 min of regional ischemia reduced infarct size (triphenyltetrazolium chloride staining) by 49%. Neither adenosine receptor blockade with 8-(p -sulfophenyl) theophylline nor the free radical scavenger N-2-mercaptopropionyl glycine inhibited the protection triggered by ethanol. In contrast, protein kinase C inhibition with chelerythrine, protein tyrosine kinase inhibition with genistein, and blockade of ATP-sensitive potassium channels (KATP) with either 5-hydroxydecanoate or glibenclamide did abolish protection. Thus, transient ethanol exposure followed by washout prior to ischemia elicits a preconditioning-like effect involving protein kinase C, at least one protein tyrosine kinase, and KATPchannels, but neither adenosine nor free radicals.