Movement of potassium between muscle and blood in response to respiratory acidosis

¹ Department of Physiology, University of Minnesota, Minneapolis, Minnesota

Experiments have been performed on anesthetized dogs in order to study 1) the movement of potassium between the gastrocnemius muscle and blood during and following 2 hr of respiratory acidosis produced by breathing 30% CO₂ in O₂, and 2) the differences between skeletal and cardiac muscle with respect to potassium movement during the first 10 min of breathing CO₂ and after return to air breathing. Plasma potassium concentrations were determined in blood samples drawn simultaneously from an artery and from either the vein draining the vascular bed of the skeletal muscle or the coronary sinus. It was found that skeletal muscle lost potassium during hypercapnia. The loss was evident much earlier and was greater if the muscle was stimulated to intermittent contraction than if it was resting. The heart began to gain potassium a few minutes after CO₂ breathing began and lost potassium shortly after return to air breathing following 11 min of hypercapnia. There was no evidence for a contribution of skeletal muscle to the high transient elevation of the arterial potassium concentrations in the early posthypercapnic period.