Chronic effect of KCl on black-white differences in plasma renin activity, aldosterone, and urinary electrolytes.

In a 10-week trial of the effect of 80 mEq KCl/day on blood pressure, the following biochemical changes were noted: plasma renin activity (PRA), originally significantly lower in blacks than whites, increased to the same level as whites after K supplementation. A similar trend was noted with aldosterone. KCl increased creatinine excretion in blacks and whites, and lowered Ca excretion in blacks. These results suggest that the low PRA found in blacks is due, at least in part, to low K intake, and not to genetic causes.