In order to study 45Ca movements within erythrocytes, a method was devised that had minimal deleterious effect on the treated erythrocytes. Agents that induce endocytosis in intact erythrocytes (primaquine, vinblastine, and chlorpromazine) caused a prompt movement of 45Ca from cytosol to membrane-associated sites. This drug-induced movement of 45Ca to membrane sites was blocked by depleting erythrocytes of adenosine triphosphate (ATP) or by incubating them with known inhibitors of endocytosis, NaF of N-ethylmaleimide (NEM). It appears that endocytosis in intact human erythrocytes involves the movement and redistribution of 45Ca from cytosol to membrane-associated sites. Therefore, in the erythrocyte, as in perhaps other cells, movement of Ca from one site to another may modulate important cellular biologic functions.

This content is only available as a PDF.