The role of hemodynamic factors on urinary calcium and magnesium excretion.

Abstract

The effects of unilateral vasodilatation and alterations in the mean arterial pressure upon the renal handling of calcium and magnesium were studied by clearance methods in dogs. Unilateral vasodilatation was produced by infusion of acetylcholine or bradykinin into the left renal artery, while arterial pressure was altered by aortic constriction, carotid occlusion and vagotomy, or by systemic infusion of angiotensin. Urinary electrolyte excretion was increased markedly by the infusion of each vasodilator and also varied directly with the mean arterial pressure, despite the absence of any significant changes in the filtered load. The fractional excretion of both calcium and magnesium correlated significantly with that of sodium. These results indicate that acute changes in renal hemodynamics modify the tubular reabsorption of divalent cations as well as alter sodium reabsorption.