Vasopressor peptides and depolarization stimulated Ca2+-entry into cultured vascular smooth muscle.

45Ca-uptake was measured in monolayers of cultured rat aortic smooth muscle cells. Sufficient extracellular 45Ca could be removed by a 90 second cold La3+ was to reveal stimulation of 45Ca-uptake by high K+-depolarization and the vasopressor peptides angiotensin II and vasopressin. The high K+-stimulated 45Ca-influx was blocked by a dihydropyridine-type Ca2+-antagonist while that stimulated by angiotensin II or vasopressin was not. The 45Ca-influx stimulated by high K+-depolarization was additive to that stimulated by angiotensin II. Vasopressin and angiotensin II stimulated 45Ca-fluxes were not additive. It is concluded that vasopressor peptides stimulate Ca2+-entry through receptor operated Ca2+-channels which are distinct from voltage gated Ca2+-channels.