Intraduodenal osmolality directly enhances insulin secretion in the rat.
To elucidate the direct effect of an intestinal osmolality on insulin release, we investigated the insulin response to intra-duodenal infusion of mannitol in rats. After the anesthesia with intraperitoneal pentobarbital sodium, one milliliter of mannitol solution (10% or 20%) was infused into the duodenum. Portal and femoral blood insulin concentrations significantly increased at 30, 60, and 120 min after intra-duodenal infusion of mannitol, although the blood glucose level did not change. Subcutaneous pre-administration of propranolol (0.4mg/kg) or metoprolol (25mg/kg) completely abolished this phenomenon. These results suggest that intestinal osmolality can directly enhance insulin secretion and that beta 1-adrenergic mechanism is involved in this phenomenon.
First Department of Internal Medicine, Tottori Univesity School of Medicine, Yonago, Japan.
T
T
Ikeda
M
M
Ishimura
H
H
Terasawa
H
H
Ochi
K
K
Fujiyama
T
T
Hoshino
Y
Y
Tanaka
H
H
Mashiba
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects; D004386:Duodenum / Q000502:physiology*; D005260:Female; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008353:Mannitol / Q000494:pharmacology*; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar
D000319:Adrenergic beta-Antagonists; D001786:Blood Glucose; D007328:Insulin; D008353:Mannitol