RELATION OF SERUM AND MUSCLE ELECTROLYTE, PARTICULARLY POTASSIUM, TO VOLUNTARY EXERCISE

Abstract

Within wide limits the amt. of K in the muscle cells does not limit the capacity of rats to swim continuously for 60 mins. Concs. of K in the serum that are abnormally low are not in themselves sufficient to produce "paralysis" or muscular weakness in normal animals. No loss of K per unit of fat-free solids from striated muscle could be demonstrated after relatively long periods of voluntary exercise. An absolute increase in muscle K was demonstrated in exercised rats injected with desoxycorticosterone acetate. Desoxycorticosterone acetate decreases the muscle K and increases muscle Na in the normal resting rat. These changes involve an apparent replacement of intracellular K by Na. The increase in the conc. of K in the serum immediately following exercise was confirmed. The conc. of K in the serum of exercised rats injected with desoxycorticosterone is decreased.