[H-3]acetylcholine release from rat amacrine-like neurons is inhibited by adenosine A(1) receptor activation

WE studied the effect of endogenous adenosine on the release of [H-3]acetyl choline ([H-3]ACh) in cultures enriched (96.4 +/- 0.4%) in rat cholinergic amacrine-like neurons, as determined by labeling with an antibody against c holine acetyltransferase. A small population of these cells also contained GABA. Using these cultures we observed that both [H-3]ACh release, which wa s largely Ca2+-dependent, and Ca-45(2+) influx, evoked by depolarization wi th 50 mM KCl, were increased when adenosine A, receptor activation was prev ented by removal of endogenous adenosine with adenosine deaminase, or by ap plication of the A, receptor antagonist DPCPX. Our results indicate that, i n cultured rat amacrine-like neurons, the activation of A, receptors decrea ses calcium influx and, thereby, inhibits [H-3]ACh release. NeuroReport 9: 3693-3698 (C) 1998 Lippincott Williams Wilkins.