Nutritional aspects of amino acid metabolism
- 1 March 1972
- journal article
- Published by Cambridge University Press (CUP) in British Journal of Nutrition
- Vol. 27 (2), 233-247
- https://doi.org/10.1079/bjn19720090
Abstract
1. Concentrations of the amino acids in the plasma of blood from the portal vein and hepatic vein and in the liver of fed rats and rats starved for 1 d or 3 d were measured. The 1 d values were compared with the equilibrium concentrations of the amino acids found in the perfusion medium during perfusion of livers from rats starved for 1 d.2. The measurements of portal–venous differences in amino acid concentrations confirmed the idea that postprandially and during starvation most of the amino acids flow from extrahepatic tissues to the liver but also showed that during starvation tryptophan, cystine, ornithine, valine, leucinc and isoleucine flow in the opposite direction, from liver to extrahepatic tissues.3. The blood levels of the non-essential amino acids fell markedly during starvation while those of the essential ones tended to be maintained. This contrasts with the pattern of changes known to take place in rats and man given low-protein diets. In the liver, changes in amino acid concentrations were generally related to those in the blood but not strictly parallel. The relative changes in amino acid concentrations in blood and liver indicate that as starvation progresses the concentrative ability of the liver is enhanced for most of the amino acids which are taken up and that the increased output of those which are released is also due to changed membrane transport.4. The changes in plasma amino acid concentrations in the blood passing through livers of rats starved for 1 d were, except for tryptophan and perhaps cystine, consistent with the extracellular changes found during perfusion of livers form rats straved for 1 d, indicating that the perfused liver influences concentrations of extracellular amino acids substantially as it does in vivo.5. The results suggest of mechanism wherby the liver may control the maintenance of the essential amino acids during starvation.Keywords
This publication has 37 references indexed in Scilit:
- Nutritional aspects of amino acid metabolismBritish Journal of Nutrition, 1972
- Nutritional aspects of amino acid metabolismBritish Journal of Nutrition, 1971
- Alanine: Key Role in GluconeogenesisScience, 1970
- Adaptation of mammalian protein metabolism to amino acid supplyProceedings Of The Nutrition Society, 1969
- Gluconeogenesis in the perfused liverAmerican Journal Of Medicine, 1966
- The Determination of Nucleic AcidsPublished by Wiley ,1966
- THE PLASMA AMINOGRAM IN KWASHIORKORThe Lancet, 1963
- THE BIOCHEMISTRY OF THE AMINO ACIDSThe American Journal of the Medical Sciences, 1958
- Effect of Digestion on Distribution of Blood Flow in the RatScience, 1957
- THE EFFECT OF ORAL PROTEIN AND GLUCOSE FEEDING ON SPLANCHNIC BLOOD FLOW AND OXYGEN UTILIZATION IN NORMAL AND CIRRHOTIC SUBJECTS 12JCI Insight, 1955