Movement of inorganic ions across the membrane of striated muscle.

The unidirectional fluxes of sodium, chloride, anid potassium across the mnembrane of striated muscle cells are described under a number of experiniental conditions. The results are compared with the predicted behavior of simple membranes. With the possible exception of chloride, it is concluded that the movements of these ions cannot be described without postulating variable permeabilities or a variable nunmber of 'carriers' or 'sites' in the membrane.