Effect of Escherichia coli hemolysin on permeability of erythrocyte membranes to calcium.

The extracellular hemolysin produced by porcine strains of E. coli effects a marked increase in the calcium permeability of erythrocyte membranes. This hemolysin promotes both calcium efflux from either calcium-loaded erythrocytes or erythrocyte ghosts and calcium accumulation during the pre-lytic period. Erythrocyte membrane calcium permeability was determined using either the radioisotope 45Ca or a calcium electrode. When similar concentrations of erythrocytes (35% packed cell volume) were treated with increasing amounts of hemolysin there was an increase in both the rate and the extent of calcium accumulation by the erythrocytes. These increases were due to increased numbers of erythrocytes becoming permeable to calcium as hemolysin concentrations increased, rather than increasing amounts of calcium being accumulated by individual erythrocytes. Hemolysins produced by porcine strains of E. coli from five geographical areas all increased calcium permeability of erythrocyte membranes.