Cyclosporin A augments vasoconstrictor-induced rise in intracellular free calcium in rat renal mesangial cells.

Pretreatment of rat renal mesangial cells with the immunosuppressive drug cyclosporin A caused a dose-dependent increase in the angiotensin II, [Arg8]vasopressin and noradrenalin-stimulated rise in intracellular free calcium as measured with quin 2. Cyclosporin A had no significant effect on basal cytosolic free calcium. However, cyclosporin A increased the basal 45Ca2+ influx. This stimulated 45Ca2+ influx was not blocked by nifedipine (10(-6) M). Cyclosporin A also augmented the angiotensin II, [Arg8]vasopressin and noradrenalin-stimulated efflux of 45Ca2+ from mesangial cells. These results suggest that cyclosporin A stimulates transmembrane Ca2+ influx in mesangial cells and also augments the vasoconstrictor-induced increases in cytosolic free calcium.