We studied the effect of nifedipine, a dihydropyridine calcium antagonist, on the hemodynamic changes induced by endothelin, in awake normotensive rats. Endothelin (0.07-1.40 nmol/kg, e.v.) caused an initial hypotensive effect, followed by long lasting hypertension. Renal blood flow was reduced immediately and still remained below basal levels, at 30 minutes after endothelin injection. Nifedipine (1 mg/kg, i.p.) significantly prevented the effect of endothelin on mean blood pressure and induced a right-ward shift in the dose response curve of renal hemodynamic changes induced by endothelin. We conclude that treatment with calcium antagonist could be very useful in all those conditions in which systemic and regional vasocostriction is provoked by endothelin.
