Release of neurotransmitter amino acids from rat brain synaptosomes and its regulation in aging

The release of neurotransmitter amino acids 14C-Asp, 14C-Glu and 14C-GABA from rat brain synaptosomes in aging is studied. It is established that K+-induced Ca2+-dependent and Ca2+-independent release of these amino acids decreases significantly in the old animals. K+ (40 mM) stimulates strongly their release for both ages, but the effect of K+ ions in old animals is less marked. Removal of Ca2+ has a greatly inhibitory effect on synaptosomal release in young as well as in old rats. The degree of inhibition does not depend on age, though it takes place at a lower level in old rats.