Insulin Secretion In Dogs Research Articles

Studies on the mechanism of xylitol-induced insulin secretion in dogs. Effect of its infusion into the pancreatic artery, and the inhibition by epinephrine and diazoxide of xylitol-induced hyperinsulinaemia.

The effect of infusion of small doses of xylitol into the pancreatic artery upon insulin release was studied in anaesthetized dogs, in order to decide whether the strong insulin-releasing effect of xylitol in dogs is mediated by a direct action of xylitol upon the islets or indirectly by some of its metabolites. Xylitol or glucose was infused at 0.5–1.0 mg/kg · min either into the femoral vein or into the superior pancreaticoduodenal artery, and the changes in plasma insulin were measured in the superior pancreaticoduodenal vein. Infusion into the pancreatic artery always resulted in a sharp increase in insulin release, whereas intravenous infusion caused no or little increase. Infusion of xylitol into the superior pancreaticoduodenal artery produced a prompt increase in plasma insulin in the superior pancreaticoduodenal vein but not in the splenic vein. These data suggest that xylitol has a direct stimulatory effect upon islet cells. — During intravenous infusion of epinephrine (1.0 μg/kg. min), plasma insulin did not increase despite intravenous administration of glucose or xylitol (0.4 g/kg). There was a rebound rise of plasma insulin after cessation of epinephrine infusion. Plasma insulin responses to intravenous injection of glucose or xylitol (0.4 g/kg) were inhibited also by the intravenous infusion of diazoxide (0.2 mg/kg · min), but this was somewhat variable among individual dogs. The suppression by epinephrine or diazoxide of both glucose and xylitol-induced hyperinsulinaemia may suggest that there is some common mechanism between the insulin-releasing effects of glucose and xylitol.

Effect of Administration of Bonito Insulin on Endogenous Insulin Secretion in Dogs, Studied by a Differential Immunoassay for Both Insulins

Effect of Administration of Bonito Insulin on Endogenous Insulin Secretion in Dogs, Studied by a Differential Immunoassay for Both Insulins

The stimulation of insulin secretion in dogs by tris (hydroxymethyl) aminomethane.

SummaryDogs infused with Tris buffer exhibited not only the hypoglycemia reported by others, but also an increase in plasma insulin level as estimated by immunoassay. The induced hyperinsulinemia was much greater in portal vein than in peripheral vein plasma samples. Both hypoglycemia and hyperinsulinemia were much more pronounced when the Tris infused was at pH 10.2 than at pH 7.4. Since Tris molecules are less ionized at higher pH, these findings are in accord with the hypothesis that hypoglycemia induced by Tris is due to this compound penetrating into and inducing release of insulin from the pancreas. The hyperinsulinemia induced by pH 10.2 Tris infusion into the pancreatic artery started later and was more variable than that induced by an equimolar infusion of glucose.

Effect of administration of ACTH on insulin secretion in dogs.

Intravenous administration of ACTH (250 μg of β1-24-corticotropin, CIBA, or 40 U of Highly Purified Corticotrophin, Organon) to dogs caused a sharp, marked and short-lived rise in plasma insulin concentrations in the pancreatic vein. Similar but smaller increases inplasma insulin were also observed in the femoral artery without concomitant changes in plasma glucose. The results provide in vivo evidence that large doses of ACTH stimulate secretion of insulin from the pancreas in dogs. (Endocrinology 81: 925, 1967)

Effects of glucagon and epinephrine on serum insulin and insulin secretion in dogs.

Glucagon, insulin-free, given ip or iv to dogs (0.1 mg/kg of body wt) caused a transient, 3- to 4-fold rise in serum immunoreactive insulin in 15-30 min, with return to normal within 120 min. Serum glucose rose and fell coincidently. The insulin-glucose ratio increased at the peak. Serum NEFA decreased during 15-60 min after glucagon injection, then increased above the initial level at 240 min. Injection of the medium alone caused no appreciable alterations in these serum constituents. That glucagon increases insulin secretion was indicated by higher concentrations of insulin in the portal vein than in superficial vein blood following iv injection of glucagon in unanesthetized dogs with indwelling portal vein cannulae. In a hypophysectomized- depancreatized dog, glucagon iv produced a rise in serum glucose but no insulin was detectable before or after injection. Epinephrine sc in normal dogs caused a rise in serum glucose, not accompanied by definite change in serum insulin. The results indicate that gluc...