Effect of pH on the water and electrolyte content of renal cells

Abstract

The effect of external pH (varying from 6.2–8.2) on the water and electrolyte contents of preparations of rabbit kidney cortex (slices and isolated tubules) was studied: 1. 1. In sodium saline, increasing external pH produced primarily a decrease in cell K +. High pH increased both the passive membrane permeability for 42K +, and also the compartmentation of K + within the cells. 2. 2. Inhibition of the Na + pump by ouabain (0.5 mM) or absence of external Na + (lithium, Tris, and choline salines) did not abolish the control of cell volume at pH 6.2 and 7.2, whereas a marked cellular swelling at pH higher than 7.5 was found. The ouabain-insensitive (and Na +-independent) volume control at pH 6.2 was dependent on metabolism, since it was inhibited by 0.1 mM dinitrophenol and anaerobiosis. 3. 3. Involvement of Ca 2+ in the ouabain-insensitive volume control was demonstrated by showing that the absence of Ca 2+, ouabain, or absence of Na +, produced a marked swelling at pH 7.2. This phenomenon was accompanied by increased extra-cellular space, due to a swelling of the basal tubular membrane. 4. 4. A correlation between cellular swelling and a decrease in cell ATP was presented. 5. 5. The results are compatible with the mechanochemical hypothesis for the ouabain-insensitive (and Na +-independent) control of cell volume. It is suggested that in this mechanism, cell (membrane) ATP and Ca 2+ are determinants of the physical properties of the membrane.