Effects of calcium antagonists on renal hemodynamics.

Recent attention has been focused on the effects of calcium antagonists on renal function. When administered in vitro to the isolated perfused kidney, calcium antagonists exhibit consistent actions permitting characterization of actions permitting characterization of their renal effects. Calcium antagonists do not affect the vasodilated isolated perfused kidney, but they do markedly alter the response of the kidney to vasoconstrictor agents. In the presence of norepinephrine, calcium antagonists markedly augment the glomerular filtration rate but produce only a modest improvement in renal perfusion. Studies using the isolated perfused hydronephrotic rat kidney model, which permits direct visualization of afferent and efferent arterioles, have demonstrated that the augmentation of the glomerular filtration rate is attributable to a preferential vasodilation of preglomerular vessels. Although the clinical implications of such observations are not fully delineated, preliminary studies in experimental animal models indicate that calcium antagonists might exert salutary effects on renal function in clinical settings characterized by an acute impairment of renal hemodynamics. It is apparent, however, that the renal hemodynamic effects of calcium antagonists commend their use in the management of essential hypertension.