title: Inhibition of protein breakdown by glutamine in perfused rat skeletal muscle.
abstract: We have assessed the effects of glutamine (Gln) availability on protein breakdown in perfused rat hindlimb by measuring net phenylalanine (Phe) production (an index of protein balance), the dilution of [15N]Phe labelling (an index of mixed protein breakdown) and rate of production of 3-methylhistidine (3-MeH) (an index of myofibrillar breakdown). 15 mM Gln significantly inhibited net protein loss and protein breakdown compared to rates obtained in its absence (net protein loss, 200 +/- 230 vs 2080 +/- 200 nmol Phe/hindlimb per h; protein breakdown, 4566 +/- 480 vs 1614 +/- 180 nmol Phe/hindlimb per h; both p less than 0.01). Insulin (100 microU/ml) inhibited protein breakdown but less than Gln. The effects on protein breakdown of Gln and insulin together were not additive, suggesting a common mode of action. Production of 3-MeH (mean 20.3 +/- 2.8 nmol/hindlimb per h) was unaffected by Gln or insulin. Gln appears to inhibit protein breakdown of soluble rather than myofibrillar protein in muscle.
authors.affiliation: Department of Physiology, University of Dundee, Scotland.
authors.forename: P A
authors.initials: PA
authors.lastname: MacLennan
authors.forename: K
authors.initials: K
authors.lastname: Smith
authors.forename: B
authors.initials: B
authors.lastname: Weryk
authors.forename: P W
authors.initials: PW
authors.lastname: Watt
authors.forename: M J
authors.initials: MJ
authors.lastname: Rennie
mesh_terms: D000818:Animals; D005260:Female; D005973:Glutamine / Q000494:pharmacology*; D006614:Hindlimb; D007700:Kinetics; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D010477:Perfusion; D010649:Phenylalanine / Q000032:analysis; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
chemical_list: D011506:Proteins; D005973:Glutamine; D010649:Phenylalanine