The overall objective of this proposal is to determine the role of ethanol in the activation of protein kinase C in the overall context of ethanol-stimulated phosphoinositide metabolism and calcium mobilization. Moreover, these membrane-related events will be correlated with ethanol-induced alteration in cellular function. Specific Aim I The effect of ethanol on signal-response coupling in human platelets will be characterized and correlated with ethanol- induced inhibition of platelet activation by physiologic agonists. Specific signal markers to be examined include inositol phosphate generation, phosphoinositide turnover and protein phosphorylation in isotopically labeled cells. Calcium mobilization will be determined in FURA-2-loaded platelets. Shape change, aggregation and secretion will be monitored in a Lumi- Aggregometer. These techniques will also serve to determine the nature of the defect in platelets obtained from human alcoholics. Specifically, it will be determined whether these platelets have a membrane-associated defect in stimulus-secretion coupling. Tolerance to ethanol in platelets from alcoholics will be determined functionally and structurally, the latter by techniques of electron spin resonance. Specific Aim II: Ethanol-induced activation of protein kinase C will be characterized in hepatocytes isolated from normal and ethanol- fed rats. One- and two-dimensional SDS-polyacrylamide gel electrophoresis will be used to measure changes in protein phosphorylation.