Blockade of cyclosporine-induced vasoconstriction by the calcium channel blocker diltiazem in dogs.

The calcium channel blocker diltiazem has been shown to reduce cyclosporine toxicity both in clinical and in experimental studies. To determine the effect of diltiazem administration on cyclosporine vasoconstriction and on renal release of endothelin, we administered cyclosporine in models of renal and hid limb autoperfusion in the dog. Infusion of cyclosporine in the hid limb (20 mg) dig diltiazem perfusion caused an average increase of 6±2 mm Hg in hind limb perfusion pressure compared with 17±2 mm Hg before diltiazem, a significant difference (p<0.05). Similarly, injections of cyclosporine (10 mg) in the kidney dwing diltiazem infusion caused an average increase of 26±4 mm Hg in renal perfusion pressure compared with 83±13 mm Hg before diltiazem infusion, a significant decrease in the renal vascular response (p<0.05)