Potassium markedly potentiates the effect of veratridine on dopamine release from rat superfused striatal ribbons.

Abstract

The effects of veratridine-induced depolarization on [3H]dopamine ([3H]DA) release in the presence of a physiological (5 mM) or a depolarizing (25 mM) concentration of K+ were studied in-vitro in rat superfused striatal ribbons. A combination of the two depolarizing agents induced a marked potentiation in the overflow of [3H]DA, giving an overall 3- to 5-fold increase in veratridine activity. This potentiation was completely antagonized by tetrodotoxin (100 nM). These studies indicated that K(+)-induced depolarization can increase the potency of veratridine in releasing dopamine from terminals.