IT HAS BEEN PROVED that the administration of chlorothiazide reduces blood pressure in hypertensive patients but not in lormotensive ones' and also that this drug affects renal hemodynamics in patients with essential hypertension.2 3 In order to determine whether there is a relationship between changes in renal hemodynamics and variations in blood pressure, a comparative study was made on the action of chlorothiazide in normotensive and hypertensive subjects.Material and Methods Eight normotensive subjects and 10 patients with early essential hypertension were studied. All hypertensive subjects were at rest and on lowsalt diet and placebo. Basal and casual blood pressure readings were taken daily and after these were stabilized the study was begun.Mean arterial blood pressure was calculated in all cases on the basis of the sum of the diastolic pressure plus one third of the pulse pressure.Glomerular filtration rate (Cin) and renal plasma floW (CPAH) were measured in both groups and osmotic clearance (Cosm) determined in all normotensive and in seven hypertensive subjects.Free water clearance (CH,o) and free water reabsorption (TCH,o) were calculated upon the basis of osmotic clearance and urine flow (V).These determinations were made before, at 60 minutes and at 90 minutes after the intravenous administration of 500 mg. of chlorothiazide in normotensive and at 40 minutes and 70 minutes in hypertensive subjects. All values were corrected to 1.73 M.2 of body surface.All normotensive and two hypertensive subjects (E.O. and S.P.) were overhydrated.Inuline was determined by a modification of Harrison's method,4 para-aminohippurate by the Smith et al. method,5 and osmolarity by the Fiske osmometer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.