Na+/K+-ATPase activity of different types of striated muscles

Na+/K+-ATPase activity was determined in striated muscles with different aerobic capacities. The underlying hypothesis was that different aerobic capacities are reflective of different contractile activity which imposes greater demands on sarcolemmal ion translocation and may thus set Na pumping capacity. The added ion translocation demands required during exercise-training on Na+/K+-ATPase activity in different muscle fiber types may require an adaptation of this enzyme. The highest and lowest Na+/K+-ATPase activity was in the heart and white gastrocnemius muscle (WG), respectively. A high linear correlation existed between Na+/K+-ATPase activity and succinate dehydrogenase activity in the six muscles studied. Exercise-training did not increase Na+/K+-ATPase activity in any of the muscles, but did increase the aerobic capacity, except in the heart and WG. It was concluded that Na+/K+-ATPase activity has a high positive correlation with the aerobic capacity of striated muscles in the rat and that the Na pump capacity does not adapt to exercise-training of 1 hr X day-1 as does aerobic capacity.