Acute effects of insulin-like growth factor I on inter-organ amino acid flux in protein-catabolic dogs.
The effects of acute administration of human recombinant insulin-like growth factor-I (rhIGF-I) on amino acid (AA) flux between hindlimbs, liver and gut were investigated in anaesthetized post-operative dogs. rhIGF-I produced about a 10-fold increase in plasma IGF-I concentrations above baseline values (P < 0.001), increased the plasma levels of glucagon and adrenaline (P < 0.05), and evoked a fall in plasma glucose (-55 +/- 8%; (P < 0.001) and plasma total AA levels (-23 +/- 8%; P < 0.05). AA flux in post-absorptive dogs under NaCl infusions was characterized by an efflux of AA from the hindlimbs (as a result of the protein-catabolic situation), an equal AA balance across the gut and an AA uptake by the liver. The administration of rhIGF-I increased hepatic AA uptake in the NaCl group from 3.51 +/- 0.8 to 7.5 +/- 0.4 mumol/min per kg (P < 0.01) and in the AA-infused group from 16.8 +/- 0.6 to 22.4 +/- 1.5 mumol/min per kg (P < 0.05), but did not influence the AA balance across hindlimbs and gut. Glucose infusions normalized the plasma concentrations of counter-regulatory hormones without influencing the inter-organ AA balances. We conclude that hypoaminoacidaemia caused by rhIGF-I infusions is the result of a stimulated AA uptake by the liver, but is unrelated to alterations of AA exchange across the hindlimbs.
Roth
E
E
Institute of Biochemical Pharmacology, University of Vienna, Australia.
Valentini
L
L
Hölzenbein
T
T
Winkler
S
S
Sautner
T
T
Hörtnagl
H
H
Karner
J
J
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D004285:Dogs; D004837:Epinephrine / Q000097:blood; D005934:Glucagon / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000378:metabolism; D009638:Norepinephrine / Q000097:blood; D011506:Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology
D000596:Amino Acids; D001786:Blood Glucose; D007328:Insulin; D011506:Proteins; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D005934:Glucagon; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine