Exchange and diffusion of potassium in kidney cortex slices

¹ May Institute for Medical Research, Cincinnati Jewish Hospital, and Department of Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio

In kidney cortex slices from rats and rabbits, cell K is known to be distributed between a diffusible compartment (K_d) and a nondiffusible pool (K_nd). In the cold, K_nd fails to exchange with extracellular Na or K despite the high permeability of the outer cell membrane to both Na and K. The K_nd compartment is freely accessible only to metabolically linked K fluxes, whereas both active and passive fluxes occur into K_d. The distribution of K between K_d and K_nd is altered by ouabain, cyanide, dinitrophenol, Ca, and other agents. This effect occurs in the absence of changes in the total K content of the cells and may represent an intracellular action of the drugs. The response of K_nd to alterations in pH in vitro corresponds to the influence of acidosis or K deficiency in vivo. Together with the previous finding of a functional difference between K_d and K_nd in vitro, the fact that the distribution of cellular potassium between two compartments can be altered by treatment of intact animals, as well as in slices, suggests that this potassium compartmentation may possess physiological significance.