INFLUENCES OF VERAPAMIL, X-537A, A-23187 AND ADENOSINE 3', 5'-CYCLIC MONOPHOSPHATE ON RELEASE OF 5-HYDROXYTRYPTAMINE FROM RAT BRAIN SLICES

Abstract

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⁺.