Cyclosporine increases calcium in kidney medulla

Treatment of rats with 20, 50 or 100 mg/kg of cyclosporine p.o. markedly increased 45Ca accumulation in kidney slices especially in medulla. The effect was related to dose and duration of treatment, and was also observed in slices of kidney medulla from cyclosporine-treated mice. Total calcium was elevated in kidney medulla of cyclosporine-treated rats so that the effect is not merely an increased exchange but a build-up of calcium in the tissue. No histopathologic evidence of cyclosporine-related cell necrosis was present in mouse kidney, showing that calcium accumulation is not dystrophic in character. Accumulation of 45Ca in slices of rat heart, liver, or brain was not affected by cyclosporine pretreatment of the animals. It is suggested that cyclosporine-induced changes in calcium metabolism in kidney medulla may influence kidney function.