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

BACKGROUND/AIMS: Recent reports in the literature suggest 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 an important factor in the stimulation of net protein synthesis during liver regeneration.