STUDIES ON THE INFLUENCE OF THE LOW SODIUM CARDIAC DIET AND THE KEMPNER REGIMEN ON RENAL HEMO-DYNAMICS AND ELECTROLYTE EXCRETION IN HYPERTENSIVE SUBJECTS 123

Abstract

A series of hypertensive patients were studied for relatively short periods on low salt Cardiac and Kempner rice diets. On the low-salt diet, no conclusive changes in renal plasma flow, renal arteriolar resistances, TmPAH, plasma volume, and serum Na and chloride occurred, but in 5 of 6 patients there occurred a decrease in G.F.R. On the rice diet there were more definitive changes. In 9 hypertensives and in one non-hypertensive patient, there occurred a significant decrease in G.F.R., R.P.F., and in F. F. In 7 of the 9, there was a decrease in renal afferent arteriolar resistance, in 5 there was a decrease in plasma vol., and in 3 of 5 a decrease in TmPAH. In the patients with initially impaired renal function, serum Na and Cl decreased. In patients on the rice diet, intraven. admn. of isotonic albumin (salt-poor) solutions did not affect G.F.R. but restored R.P.F. to full diet values: in contrast, intraven. concd. Na solns. were associated with significant increases in both G.F.R. and R.P.F., whereas intraven. Dibenamine had no renal hemodynamic effects. On regular, low salt, and Kempner rice diets electrolyte excretion tended to parallel intake. The hypertensive subjects, however, exhibited a proportionality between electrolyte excretion and urine volume during water and moderate mannitol diuresis, in contrast to normal subjects. This electrolyte leakage occurred even in subjects with normal TmPAH''s, and may be the earliest sign of renal tubular damage in hypertension. The possible role of alterations in renal hemodynamics, especially G.F.R., along with changes in adrenal cortical hormone secretion, etc., in conserving electrolyte during restricted salt intake is discussed from the point of view of glomerular tubular imbalance.