Effects of chronic ethanol ingestion on arachidonic acid metabolism in rat tissues and in vitro effect of ethanol on camp in platelets

Effects of chronic ethanol ingestion (3 weeks) on the capacity of peritoneal macrophages, lung and heart tissues, to metabolize endogenous arachidonic acid (AA) in rats, and the in vitro effect of ethanol on 3′-5′ cyclic adenosine monophosphate (CAMP) levels in rat platelets were studied. Peritoneal resident macrophages were stimulated by calcium ionophore (A23187) and levels of 5-hydroxyeicosatetraenoic acid (5-HETE), leukotriene B₄ (LTB₄) and PGE₂ were measured by radioimunoassay. There were no differences in levels of the eicosanoids synthesized by macrophages between the ethanol treated and the control group. There were also no differences found in levels of the eicosanoids synthesized by heart or lung homogenate between the two groups. These results suggest that chronic ethanol ingestion does not alter the capacity to synthesize the eicosanoide from the endogenous precursor in tissues studied here. Preincubation of ethanol with platelet rich plasma resulted in a dose dependent increase in cAMP levels. The well documented inhibitory effects of ethanol in vitro on aggregation and AA metabolism in platelets may be due to the enhanced cAMP levels.