Relation of Intracellular Ca²⁺ to Retention of K⁺ by Liver Slices

Abstract

CALCIUM ions are necessary for the maintenance of the normal, low permeability of cell plasma membranes^1–3: if animal cells are incubated in media free of Ca²⁺ the passive permeability of the membranes increases, and the cells are unable to maintain their normal concentration gradients of K⁺ and Na⁺ (refs. 4, 5). Recent work has suggested, however, that a raised level of intracellular Ca²⁺ specifically increases the passive permeability of erythrocyte membranes to K⁺. Liver cells possess an energy dependent mechanism which can bring about the net extrusion of Ca²⁺ that has accumulated during incubation at 1° C (refs. 7, 8). It was therefore of interest to examine the relationship between the lowering of intracellular Ca²⁺ thus produced and the accompanying recovery of the K⁺ and Na⁺ composition of the cells.