Co‐ordinated Increase of Sodium Leak and Sodium Pump in Hereditary Spherocytosis

Summary The presence of an increased sodium leak into hereditary spherocytes up to three times normal has been confirmed from measurement of 22Na+ influx into red cells. 22Na+ influx was not identical to the net inward leak of Na+ but the two kept a constant relationship since influx was about double the net Na+ gain in both normal and abnormal cells incubated with ouabain. The intracellular concentration of Na+ ions in fresh cells from hereditary spherocytes was identical to that in normal red cells. Hereditary spherocytes showed increased maximal activity of a membrane ATP‐ase inhibited by ouabain and the Na+ concentration giving half‐maximal activation of this ATP‐ase was the same for spherocytes and normal cells. When the 22Na+ influx into red cells from nine patients with hereditary spherocytosis was compared with maximal activity of cation pump ATP‐ase in the same cells a significant correlation was obtained (r= 0.78, P > 0.01). The results indicate some linkage between the increase in the Na+ leak and functional number of active cation pumps in the membrane of hereditary spherocytes.