The linkage of sodium, potassium, and ammonium active transport across the human erythrocyte membrane

Abstract

1. 1. The net transport of potassium and sodium across the human erythrocyte membrane were observed at 37° in cells prepared by cold storage and fortified with nucleoside. Passive transport was minimized by adjustment of sodium and potassium concentrations in the medium. Active transport was distinguished from passive transport by the use of strophanthin, which stops active transport specifically. 2. 2. The active transport of potassium inward and sodium outward occured only at a ratio which was constant over a wide range of rates and independent of extracellular and intracellular sodium and potassium concentrations. Two atoms of potassium wer e transported inward for every three atoms of sodium that were tramsported outward. 3. 3. Ammonium appeared to substitute directly for potassium adn required a concentration 3 to 7 times greater than potassium to produce a comparable effect. 4. 4. These findings indicate that active potassium and sodium transport across the human erythrocyte membrane are parts of a single tightly-linked system.