Vasopressin rapidly stimulates Ca2+ efflux from intracellular pool in quiescent Swiss 3T3 cells

Addition of the neurohypophysial nonapeptide [Arg8]vasopressin to 45Ca2+-loaded quiescent cultures of Swiss 3T3 cells or diploid mouse embryo fibroblasts causes a rapid increase (within seconds) in the rate of 45Ca2+ efflux from the cells. This reflects the release of 45Ca2+ from an intracellular store that is partly or entirely derived from mitochondria and leads to a marked decrease (52%) in the intracellular 45Ca2+ content of the cultures under equilibrium 45Ca2+ conditions. The effect is dose dependent, specific, and blocked by a vasopressor antagonist. Prolonged pretreatment with vasopressin that renders the cells unresponsive to the mitogenic effects of the hormone also blocks the Ca2+ response. The results suggest that Ca2+ fluxes may be involved in the mechanism of mitogenic action of vasopressin in Swiss 3T3 cells.