EFFECT OF ASCORBIC-ACID ON RELEASE OF ACETYLCHOLINE FROM SYNAPTIC VESICLES PREPARED FROM DIFFERENT SPECIES OF ANIMALS AND RELEASE OF NORADRENALINE FROM SYNAPTIC VESICLES OF RAT-BRAIN

Low concentrations of L-ascorbic acid caused release of acetylcholine from isolated synaptic vesicles (rat, guinea-pig and rabbit) in the presence of 2mM ATP, 2 mM MgCl2 and 10-5 M CaCl. The half maximum effect was obtained with about 2 to 2.5 ωM L-ascorbic acid, and the effect was inhibited by addition of 1mM EGTA. The release of noradrenaline from rat synaptic vesicles was also enhanced by L-ascorbic acid, but the concentration for half maximal stimulation was about 20 ωM, indicating that noradrenaline release was less sensitive to L-ascorbic acid than acetylcholine release. The physiological function of L-ascorbic acid in the brain is discussed in relation to release of transmitters. © 1979.