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

Changes in cell volume and alanine, Na+ and K+ concentrations and fluxes were studied in rat isolated hepatocytes or perfused liver. Addition of 10 mM 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 rôle of extracellular anions was investigated: alanine transport was not affected by replacement of Cl- and HCO-3 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.