AJP - Endocrinology and Metabolism, Vol 242, Issue 5 343-E351, Copyright © 1982 by American Physiological Society
Interaction of arginine and gastric inhibitory polypeptide on insulin release in man
D. Elahi, G. S. Raizes, R. Andres, R. J. Hershcopf, D. C. Muller, J. D. Tobin and D. K. Andersen
The interrelations of the insulin secretagogues, glucose, arginine (Arg),
and gastric inhibitory polypeptide (GIP) were quantified in six normal
young men in five sets of experiments with the hyperglycemic clamp
technique (125 mg/dl above basal glucose levels for 2 h). After 60 min of
intravenous glucose alone, one of the following was added: A) oral glucose
(OG) (40 g/m2); B) 15 g.m-2.h-1 Arg infusion; C) 15 g.m-2.h-2 Arg infusion
and OG; D) 7.5 g.m-2.h-1 Arg; E) 7.5 g.m-2.h-1 Arg and OG. The clearance
rate of Arg was similar for B, C, D, and E. In all experiments, plasma GIP
levels were unchanged from the basal level during the 1st h. The increases
in plasma GIP levels in experiments C and E were similar to the increase
when OG alone was ingested (A). When the stimulatory effect of the
secretagogue(s) alone on insulin (IRI) is computed, the increase due to OG
(A) and to 7.5 g.m-2.h-1 Arg (D) were similar and additive (A + D
approximately equal to E). However, the stimulatory effect of 15 g.m-2.h-1
Arg + OG (C) on IRI was not significantly greater than 15 g.m-2.h-1 alone
(B). The 15 and 7.5 g.m-2.h-1 Arg infusion produced different patterns of
insulin and glucagon secretions. At the lower dose, the response of both
hormones to Arg decreased with time. Arg and GIP act through a similar and
possibly common mechanism on the beta-cell. However, only Arg was found to
be alpha-cytotropic. GIP does not appear to influence the metabolic
clearance of Arg. The dose-response relationships to Arg of the beta- and
alpha-cell appear similar.
