title: Arginine enhances glycogen synthesis in response to insulin in 3T3-L1 adipocytes.
abstract: The present study was undertaken to define the role of L-arginine (L-Arg) in glucose metabolism in differentiated 3T3-L1 adipocytes in culture. L-Arg alone had no effect on 2-deoxyglucose uptake or basal glycogen synthesis, but this amino acid increased by 153 +/- 10% (P < 0.01) the incorporation of glucose into glycogen in insulin-treated cells. L-Glutamate (L-Glu), a major metabolite of L-Arg, also enhanced insulin-stimulated glycogen synthesis. The response to insulin was not altered by L-lysine (L-Lys), but the effect of L-Arg was markedly attenuated by L-Lys. Cell incubation with L-Arg markedly enhanced arginase-mediated urea synthesis, whereas L-Lys abolished this response. The stimulatory effect of L-Arg on insulin-stimulated glycogen synthesis did not appear to be accounted for by the generation of polyamines or the production of nitric oxide, both potentially derived from the enzymatic conversion of L-Arg. In the presence of insulin, cellular ATP levels were significantly increased by L-Arg, L-Glu, and L-Lys as well. These data suggest that metabolic degradation of L-Arg not related to citric acid cycle activity is important in the mechanism by which L-Arg enhances insulin-stimulated glycogen synthesis.
authors.affiliation: Diabetes Unit, National Institute on Aging, Baltimore, Maryland 21224, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Egan
authors.forename: T E
authors.initials: TE
authors.lastname: Henderson
authors.forename: M
authors.initials: M
authors.lastname: Bernier
mesh_terms: D016475:3T3 Cells; D000255:Adenosine Triphosphate / Q000378:metabolism; D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D002460:Cell Line; D005947:Glucose / Q000378:metabolism; D018698:Glutamic Acid / Q000494:pharmacology; D006003:Glycogen / Q000096:biosynthesis*; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology*; D008239:Lysine / Q000494:pharmacology; D051379:Mice; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D019323:omega-N-Methylarginine
chemical_list: D007328:Insulin; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D018698:Glutamic Acid; D000255:Adenosine Triphosphate; D006003:Glycogen; D001120:Arginine; D005947:Glucose; D008239:Lysine