Effects of Chlorothiazide on Renal Hemodynamics

Abstract

A comparative study was made of the acute effect of chlorothiazide upon renal hemodynamics in eight normotensive subjects and 10 patients with early essential hypertension. It was observed that blood pressure remained unchanged in normotensive subjects but was significantly reduced in hypertensive patients. Glomerular filtration rate was decreased similarly in both groups, whereas renal plasma flow was not modified in either. Osmotic clearance increased in all subjects, free water clearance diminished in normotensive (overhydrated) subjects, whereas in the hypertensive (not overhydrated) patients free water reabsorption increased. It is concluded that chlorothiazide reduces blood pressure in hypertensive patients but not in normotensive persons; that the kidney reacts in the same fashion in normotensive and hypertensive subjects under the action of the drug; and that the alterations in renal function observed with its use in hypertensive subjects are probably unrelated to changes in blood pressure.