Effect of alanine transport on ionic fluxes across the cell membrane in rat liver

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Abstract
Changes in cell volume and alanine, Na+ and K+ concentrations and fluxes were studied in rat isolated hepatocytes or perfused liver. Addition of 10 him alanine elicited a noticeable entry of Na+ which accumulated into the cells, along with a leakage of cell K+. Concurrently, the cell volume was 13 % increased. These processes were also present with perfused livers in which alanine uptake, Na+ entry and cell swelling were proportional to the induction of the A system. K+ efflux was parallel to cell swelling and occurred very early after exposure of liver cells to alanine (and was transitory). The role of extracellular anions was investigated: alanine transport was not affected by replacement of Cl− and HCO3− by a permeant anion whereas it was inhibited with the non-permeant anion isethionate. The present results indicate that the disturbances of the ionic gradients consecutive to alanine transport in isolated hepatocytes also operate in the liver organ itself. The possible implications of these phenomenons are discussed.