ASCORBIC-ACID INCREASES SYNAPTOSOMAL POTASSIUM-INDUCED DOPAMINE RELEASE

ON synaptosomes prepared from striata of mice, increasing concentratio ns of ascorbic acid (from 0.01 mM to 0.5 mM) did not modify the H-3-do pamine uptake. However, at the 0.1 mM concentration, ascorbic acid inc reased the potassium-induced release of H-3-dopamine by synaptosomes p reviously loaded with the amine. This effect was dependent on the pres ence of Ca2+ in the superfusion medium and was not shared by dehydroas corbic acid (from 1 mM to 0.01 mM). This effect of ascorbic acid, whic h occurs in the range of its endogenous concentrations, suggests that it is a putative modulator of dopaminergic transmission.