Inhibitory effect of ethanol on 5-hydroxytryptamine (serotonin) uptake in human blood platelets in vitro

Ethanol in concentrations higher than 10(-2) M (or about 0.5% W/W) inhibited the uptake of 14C-5-hydroxytryptamine (serotonin) in human blood platelets in an artificial, protein-free medium, by a non-competitive mechanism. The inhibition was not influenced by the alcohol dehydrogenase inhibitor methylpyrazole (10(-3) M). In concentrations up to 0.1 M, ethanol had no effect on 5-HT efflux from the platelets. At higher concentrations, ethanol increased efflux. Inhibition of 5-HT uptake was found to increase progressively in the sequence methanol - ethanol - propanol - butanol.