Effects of potassium chloride on plasma renin activity during sodium restriction in normal man

Previous studies have suggested that large intakes of potassium (K) will suppress plasma renin activity (PRA) in normal man. The effect of more modest intakes of K on PRA is unclear. The present study was designed to compare the PRA in 11 normal volunteers maintained on an electrolyte-free diet (7000 J), with and without the addition of 50 mEq/day of potassium chloride (7000 J + KCl), well within the limits of usual dietary consumption. Control recumbent and 2 hr of upright PRA determinations were made by radioimmunoassay prior to the initiation of either the 7000 J diet or the 7000 J + KCl diet and on the fourth day of the diet, at a time when urinary sodium, K, and chloride excretions were near intakes. Mean (+/- S.E.M.) PRA's are indicated in Table II. There are significant (p less than 0.01) differences between (1) all respective recumbent and upright posture positions and (2) before and after the administration of 7000 J and 7000 J + KCl. However, there are no significant differences between (1) control periods or (2) before and after the addition of KCl to the electrolyte-free diet. We conclude from these studies that K, given in modest amounts, has no inhibiting effect on PRA.