Abstract. A continuous intravenous infusion of L-leucine (300 μmol min-1) was given to 12 healthy females over a 2 1/2 h period. Arterial plasma concentrations of amino acids and the keto acids of the branched-chain amino acids (BCAA) were measured. In six subjects muscle biopsies were taken before and at the end of the infusion for determination of intracellular (i.c.) free amino acid concentrations, and leg exchange of amino acids was measured. During infusion the plasma level of leucine rose sixfold. Approximately 40% of the infused amount was taken up by muscle. Of this, half was accumulated intracellularly, where the free leucine concentration increased from basal 190 ± 22 to 580 ± 110 μmol 1-1 ICW (intracellular water) at the end of infusion. The concentrations of most other amino acids, above all the other BCAA and the aromatic amino acids, decreased, by 17–48% in the i.c. pool and by 17–79% in plasma. The plasma level of ketoisocaproic acid (KIC), the keto acid of leucine, increased in parallel with that of leucine. The concentration of keto valine, ketoisovaleric acid (KIV), decreased by 75%, whereas the keto acid of isoleucine, ketomethylvaleric acid (KMV), was unchanged. Leg release of alanine decreased significantly, whereas the exchange of other amino acids were unchanged. Taken together, decreased i.c. and plasma concentrations but unchanged leg exchange of tyrosine and phenylalanine suggest i.c. accumulation of protein. It can be calculated that approximately 40% of the leucine taken up by muscle was accumulated in the intracellular free pool, some 20% could have been incorporated into protein and 40% was probably oxidized.

Influence of leucine infusion on intracellular amino acids in humans / Alvestrand, A; Hagenfeldt, L; Merli, Manuela; Oureshi, A; Eriksson, Ls. - In: EUROPEAN JOURNAL OF CLINICAL INVESTIGATION. - ISSN 0014-2972. - STAMPA. - 20:(1990), pp. 293-298. [10.1111/j.1365-2362.1990.tb01858.x]

Influence of leucine infusion on intracellular amino acids in humans.

MERLI, Manuela;
1990

Abstract

Abstract. A continuous intravenous infusion of L-leucine (300 μmol min-1) was given to 12 healthy females over a 2 1/2 h period. Arterial plasma concentrations of amino acids and the keto acids of the branched-chain amino acids (BCAA) were measured. In six subjects muscle biopsies were taken before and at the end of the infusion for determination of intracellular (i.c.) free amino acid concentrations, and leg exchange of amino acids was measured. During infusion the plasma level of leucine rose sixfold. Approximately 40% of the infused amount was taken up by muscle. Of this, half was accumulated intracellularly, where the free leucine concentration increased from basal 190 ± 22 to 580 ± 110 μmol 1-1 ICW (intracellular water) at the end of infusion. The concentrations of most other amino acids, above all the other BCAA and the aromatic amino acids, decreased, by 17–48% in the i.c. pool and by 17–79% in plasma. The plasma level of ketoisocaproic acid (KIC), the keto acid of leucine, increased in parallel with that of leucine. The concentration of keto valine, ketoisovaleric acid (KIV), decreased by 75%, whereas the keto acid of isoleucine, ketomethylvaleric acid (KMV), was unchanged. Leg release of alanine decreased significantly, whereas the exchange of other amino acids were unchanged. Taken together, decreased i.c. and plasma concentrations but unchanged leg exchange of tyrosine and phenylalanine suggest i.c. accumulation of protein. It can be calculated that approximately 40% of the leucine taken up by muscle was accumulated in the intracellular free pool, some 20% could have been incorporated into protein and 40% was probably oxidized.
1990
Amino acids
01 Pubblicazione su rivista::01a Articolo in rivista
Influence of leucine infusion on intracellular amino acids in humans / Alvestrand, A; Hagenfeldt, L; Merli, Manuela; Oureshi, A; Eriksson, Ls. - In: EUROPEAN JOURNAL OF CLINICAL INVESTIGATION. - ISSN 0014-2972. - STAMPA. - 20:(1990), pp. 293-298. [10.1111/j.1365-2362.1990.tb01858.x]
File allegati a questo prodotto
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/450903
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? 8
  • Scopus 44
  • ???jsp.display-item.citation.isi??? 43
social impact