CHRONIC SODIUM CHLORIDE TOXICITY: THE PROTECTIVE EFFECT OF ADDED POTASSIUM CHLORIDE

Abstract

Concurrent control and high salt diets produced survival curves expected from earlier experiments maintaining young male rats at constant temperature on complete purified diets and demineralized water ad libitum throughout life. Adding 2.9% KC1 to diets containing 5.6% NaCl increased the 50% survival time some 7 months (approximately 21 years for man). These K protected rats outlived the controls, posing the question that the control diet may be suboptimal for K. Half of the rats eating 8.4% NaCl with 4.7% KC1 survived 8 months longer than their counterparts. There was a high incidence of the early nephrotic syndrome among the rats eating 9.8% NaCl with 5.6% KC1. Those rats surviving this critical 2-4 month period paralleled the controls for the ensuing 10 months and, from the 11th month, larger percentages of their original group were surviving than of their counter parts eating 9.8% NaCl. There was no apparent effect of added KC1 on the modest hypertension of lower levels (5.6% of added dietary salt). Extra potassium KC1 lowered the high hypertension accompanying high NaCl, 8.4 and 9.8%, feeding to intermediate levels for a prolonged period, from 8-20 months. In the total exchangeable Na measurements at 8-10 months the 5.6% NaCl groups with or without added KC1 were similar to each other and to the 2 control groups. At levels of 8.4 and 9.8% NaCl the blocking effect of KC1 was marked. At the 5.6% NaCl level the added KC1 did not exhibit blocking effects in the total exchangeable Na or systolic blood pressure although the protection afforded survival was significant. At the 8.4% NaCl and 9.8% NaCl levels the blocking effects of added KC1 in the total exchangeable Na were also reflected in the lowering of high hypertension measured after the same period, 8-10 months, on the experimental regimen.