Arginine enhances glycogen synthesis in response to insulin in 3t3
-l1 adipocytes.
Egan, Josephine M., Terrance E. Henderson, and Michel Bernier.
Diabetes Unit, Laboratory of Clinical Physiology, National
Institutes on Aging, Baltimore, Maryland 21224
APStracts 2:0028E, 1995.
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 while 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.
Received 22 November 1994; accepted in final form 13 February
1995.
APS Manuscript Number E483-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.