Influences of verapamil, X-537A, A-23187 and adenosine 3',5'-cyclic monophosphate on release of 5-hydroxytryptamine from rat brain slices.

Influences of verapamil, X-537A, A-23187 and cyclic-AMP on the release of [3H]-5-HT taken up into rat brain slices, were examined. Incubation with 40 mM KCl induced tritium release which was dependent on the presence of Ca2+. Verapamil, which blocks Ca2+ influx in excitable tissues, decreased potassium-induced release of 5-HT. Tritium release induced by ionophore X-537A was not dependent on extracellular Ca2+ while that induced by A-23187 required Ca2+. Cyclic-AMP, dibutyryl cyclic-AMP and theophylline did not significantly stimulate 5-HT release either in the presence or absence of Ca2+.