Ethanol stimulates basal and serotonin-induced formation of [32P]phosphatidic acid in human platelets

The addition of serotonin to preparations of 32P-labelled human platelets resulted in a time- and dose-dependent hydrolysis of [32P]phosphatidylinositol 4,5-bisphosphate (PIP2) and formation of [32P]phosphatidic acid (PA). This response was inhibited by the serotonin2 receptor antagonist ritanserin, indicating that the stimulation was mediated via the serotonin2 receptor. The addition of 50-150 mM of ethanol prior to stimulation with 10(-5) M serotonin resulted in an increased accumulation of [32P]PA, but had no effect on [32P]PIP2. Ethanol stimulated [32P]PA formation at all serotonin concentrations studied (10(-7)-10(-5) M). Furthermore, in the absence of serotonin, ethanol increased basal [32P]PA formation.