In vivo amino acid fluxes in regenerating liver after two-thirds hepatectomy in the rat

Background/Aims: Recent reports in the literaturesuggest that liver cell swelling following amino acid influx exerts anabolic and anti-catabolic effects. We have tested the possibility that rapid liver growth after partial hepatectomy is promoted by an increased amino acid-influx and that this is associated with an increased hepatic water content and a decreased rate of proteolysis. Methods: Two-thirds hepatectomy was performed in rats. Plasma liver flow and amino acid fluxes were measured after 24 or 48 h. Results: Plasma liver flow was increased 24 and 48 h after partial hepatectomy or sham-operation in pair-fed animals. At these time points, in both groups there was a specific two- to threefold increased net hepatic uptake of the amino acids alanine and glycine, both being transported by the sodium-coupled amino acid transport system A/ASC. No changes in uptake of system N transported amino acids were observed. Both in partially hepatectomized and sham-operated pair-fed animals, the hepatic uptake of alanine and glycine was accompanied by a minor increase in tissue water (from 68 to 70%). Proteolysis, measured by leucine efflux, was only reduced in regenerating livers. Conclusions: We conclude that cell swelling is not animportant factor in the stimulation of net protein synthesis during liver regeneration.