Studies on the permeability of erythrocytes

Abstract

The permeability of the erythrocytes of the man, guinea pig, rat, rabbit, pig, ox, and cat to Na and K on. suspension in a non-electrolyte medium has been investigated by direct chemical methods. The cells of the man, guinea pig, and rat are permeable to K, and those of the ox and cat to both Na and K under these conditions. The cells of the man, guinea pig, and rat give smooth curves on plotting their K contents against time of suspension; however, there is a falling off with time in the rate of loss of K, so that a stationary state is reached at K contents remote from the equilibrium position. This auto-inhibition is tentatively ascribed to the building up of a potential gradient which eventually inhibits the further migration of K. The erythrocytes of the rabbit and pig show little tendency to lose K under the same conditions, the loss after 7 hrs. of suspension may be as low as 4% compared with a loss of nearly 70% with human cells. The change in the membrane causing the permeability is a reversible one in that the escape of K may be inhibited, after it has begun, by the addition of NaCl to the non-electrolyte medium. Human cells are very sensitive to salt conc. of the suspension medium when this is less than 0.02 M; at a conc. of 0.09 M the non-electrolyte effect ceases. Alkaline buffers added to the suspension medium reduce the rate of loss of K to a smaller extent than an equivalent quantity of NaCl; acid buffers have the reverse effect. There is an apparent correlation between the tendency of the erythrocytes of different spp. to agglutinate in a non-electrolyte medium and the induced permeability to cations; the agglutination itself is not the cause of the permeability but may be symptomatic of a change in the surface of the cell which allows cations to cross the membrane.