Cell volume regulatory responses of isolated perfused rat liver. The effect of amino acids.
1) Addition of glutamine, glycine, alanine, serine, phenylalanine, proline at a concentration of 3mM, each, or of an amino-acid mixture resembling the physiological amino-acid composition of portal venous blood, to influent perfusate of isolated perfused rat liver led to a 4-6% increase of liver mass without increase of the [3H]inulin space, and biphasic K+ movements across the plasma membrane. These K+ movements consisted of an initial net K+ uptake (0.4-0.9 mumol X g-1 liver) for about 2 min, being followed by a net K+ release (1.0-2.8 mumol X g-1 liver) during the next 10 min. Withdrawal of the amino acids from influent perfusate caused a slow net K+ reuptake by the liver and restored the initial liver mass. No effects on liver mass and K+ fluxes were observed following addition of glutamate or glucose at a concentration of 3mM, each. 2) Aminooxyacetate did not affect the alanine (3 mM) induced increase in liver mass. However, in presence of aminooxyacetate the alanine-induced net K+ release from the liver (i.e. K+ release from 2-10 min minus initial K+ uptake) increased from 0.1 to 2.2 mumol X g-1 liver, whereby simultaneously the alanine tissue level rose from 6.8 to 13.3 mumol X g-1 (corresponding to an increase of the intracellular alanine concentration from about 12 to 25 mM) in presence of aminooxyacetate. 3) When livers were perfused with different glutamine concentrations, a maximal increase in liver mass of 5-6% was observed at glutamine concentrations above 1.5-2mM. A halfmaximal increase in liver mass was observed at 0.6-1.0mM glutamine in influent, i.e. at the physiological portal glutamine concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
Wettstein
M
M
Medizinische Universitätsklinik Freiburg.
vom Dahl
S
S
Lang
F
F
Gerok
W
W
Häussinger
D
D
D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport; D005973:Glutamine / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009994:Osmolar Concentration; D010477:Perfusion; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000596:Amino Acids; D005973:Glutamine; D011188:Potassium