Stimulus-secretion coupling of arginine-induced insulin release. Effect of 2-aminoisobutyric acid upon ornithine decarboxylase activity and insulin secretion.
Recent studies have revealed that, in rat pancreatic islets, exogenous L-arginine or L-ornithine are converted to putrescine, spermidine and spermine. The possible role of polyamine generation in the secretory response of the B-cell to the cationic amino acids was investigated in islets either preincubated for 90 min with 2-aminoisobutyric acid (AIB; 10 mM) or removed from rats injected intraperitoneally with AIB (2.4 mmol) 210 min before sacrifice. Although AIB failed to exert any direct effect upon the secretory response of the islets to either L-arginine or L-ornithine, preincubation of the islets with AIB increased both the activity of ornithine decarboxylase and, to a modest extent, the insulinotropic action of L-arginine and L-ornithine. Likewise, after treatment with AIB in vivo, the activity of ornithine decarboxylase increased tenfold or more in kidney, liver, pancreas, parotid gland and islet homogenates. The secretory response to D-glucose was little affected in islets removed from AIB-treated rats, but the insulinotropic action of L-arginine and L-ornithine were slightly increased. These findings suggest that the de novo generation of polyamines only plays a restricted role in the secretory response of islet cells to L-arginine and L-ornithine.
Sener
A
A
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Owen
A
A
Malaisse-Lagae
F
F
Malaisse
W J
WJ
D000596:Amino Acids / Q000494:pharmacology; D000621:Aminoisobutyric Acids / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D000518:Eflornithine / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D009955:Ornithine Decarboxylase / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats
D000596:Amino Acids; D000621:Aminoisobutyric Acids; D007328:Insulin; C100049:2-aminoisobutyric acid; D001120:Arginine; D005969:Glutamate Dehydrogenase; D009955:Ornithine Decarboxylase; D005947:Glucose; D000518:Eflornithine