The permeability of the peritubular cell membrance fork⁺, HCO₃^-, Na⁺ and cl^- in the rat kidney proximal tubule

Abstract

Using a semi-floating glass microelectrode, the permeability of the peritubular membrane for Na, K. HCO₃ and Cl was studied in the rat kidney proximal tubule in vivo. The magnitude of the change in membrane and transepithelial p.d. due to peritubular ionic replacement was analyzed by means of an equivalent circuit analysis. The results of the present study showed that the peritubular p.d. is composed mostly of the diffusion p.d. of K and HCO₃. The contribution of Na and Cl to the membrane current appears to be negligible. The transference number of the peritubular cell membrane was 0.57 for K, 0.42 for HCO₃ and less than 0.01 for Na.