Muscle Electrolytes in Acid and Alkaline Solutions

¹ From the Department of Physiology, The University of Rochester School of Medicine and Dentistry, Rochester, New York

Isolated frog muscles were equilibrated in solutions of varying pH and were then analyzed for potassium, sodium and sometimes chloride, phosphate, or bicarbonate. It was found that acid applied outside the muscle causes in most cases an increased loss of K. Over the physiological pH range this was also true of Na in experiments in which the complication of the extracellular space was minimized by replacing 90% of the NaCl of the solution by sucrose. In the other experiments the variations were such that it was impossible to establish any regular effect of pH on the movements of sodium. Except at a pH below 2 or above 12 the Na did not appear to exchange with K in response to injury. It is suggested that the Na pump in muscle works better when the Na is being moved into a more acid solution. It is concluded that muscle neutralizes external acid in part by loss of K, sometimes by loss of Na, and to some extent by gain of chloride. There was a slightly increased loss of phosphate and bicarbonate from muscle in the more acid solutions but no evidence of an increase in the extracellular fluid as measured by inulin.