Effects of protamine and strophanthin on mitochondrial potassium, sodium and water

¹ Western Reserve University, Department of Physiology, Cleveland, Ohio

A study was made of the effects of certain agents, which inhibit potassium transport in intact cells, on the potassium, sodium and water metabolism of isolated mitochondria. Protamine (4 mg/100 ml) induced swelling in rat liver and kidney mitochondria and impaired the ability of these mitochondria to concentrate potassium. These actions appeared to be associated with the uncoupling of oxidative phosphorylation. Protamine was without effect on the mitochondrial sodium concentration. Strophanthin at extremely high concentrations (1 gm/100 ml) was also found to induce swelling of rat liver, kidney and heart mitochondria and to interfere with the ability of the mitochondria to concentrate potassium. There was a tendency for mitochondrial sodium concentration to be elevated. It is concluded that the actions of protamine and strophanthin on mitochondria are qualitatively and quantitatively different from the actions of these substances on intact cells and that there are basic differences between the potassium concentrating mechanisms in mitochondria and in intact cells.