Following blockade of plasma membranepotassiumchannelswith barium or tetraethylammonium chloride, release ofcholecystokininwas increased in an intestinal cell line (STC-1). Treatment with calcium channel blockers inhibited barium- or TEA-inducedsecretion. Barium chloride also stimulated 45Ca efflux fromSTC-1cells. Whole cell patch clamp recordings revealed a voltage-activated, L-type calcium current. We conclude that, inhibition of basally activepotassiumchannelsmay depolarizeSTC-1cells, producing activation of voltage-gated calcium influx pathways. Influx of calcium may lead to a release of intracellular calcium which stimulatescholecystokininsecretion.