The restoration of ATP synthesis may explain the protective effect of calcium antagonists against cyclosporine A nephrotoxicity.

Cyclosporine A at pharmacological doses decreases the rate and yield of ATP synthesis in rat mitochondria. This action seems to be due to the mitochondrial calcium storage induced by the drug. If such an effect occurs in vivo, the ATP deficit will affect calcium extrusion pumps, so triggering vasoconstriction which is the major side effect of Cyclosporine A. Calcium antagonists (Nifedipine and Verapamil) at least partially correct this effect on ATP synthesis: this finding may be related with the beneficial clinical effect conferred on Cyclosporine A toxicity by calcium antagonists. This effect of calcium antagonists may be due to an interaction with Cyclosporine A at the level of mitochondrial calcium efflux.