Effects of chronic potassium deficiency on plasma renin activity.

Serial determinations of plasma renin activity, sodium balance, urinary potassium excretion rate, and plasma sodium and potassium concentration were done in five dogs during dietary-induced potassium depletion and repletion. Duration of depletion for the different animals ranged from 5 to 7 wk. Plasma renin activity increased in all animals during depletion, with rises being demonstrated as early as the 1st depletion day in two of the dogs. Maximum values in the five dogs were recorded from the 2nd to the 28th day of depletion. Early in depletion, changes in renin activity did not correlate with changes in sodium balance. Late in the course of depletion, plasma renin activity decreased concurrently with a progressive retention of sodium. However, in every case increased renin activity persisted throughout depletion despite development of sodium retention sufficient to inhibit renin release in normal dogs. Potassium repletion resulted in a prompt decrease in renin activity to predepletion values. This study indicates that potassium deficiency has a stimulatory effect on renin release that is independent of any effect on sodium balance.