Effects of an ionophore, A23187, on the surface morphology of normal erythrocytes.

A23187, an ionophore which selectively transports divalent cations across biologic membranes, was found in previous studies to cause exchange of calcium for hydrogen ions in erythrocytes, loss of potassium, and a decrease in cell volume due to escape of water without hemolysis. The present investigation has evaluated the influence of A23187 on erythrocyte morphology in the scanning electron microscope. The findings demonstrate that A23187 causes a time- and concentration-dependent conversion of biconcave erythrocytes into echinocytes and spheroechinocytes. The changes induced in erythrocytes by the ionophore required the presence of extracellular calcium. Red cells exposed to ionophore at low temperature were moderately resistant to its effects, and low pH (5.5 or less) virtually blocked the action of the drug. The findings support an important role for calcium in maintaining the discoid configuration of normal erythrocytes.