Glucagon Is Paradoxically Secreted at High Concentrations of Glucose in Rat Pancreas Perfused With Diazoxide

Diabetes Nutr Metab. 2002 Aug;15(4):260-4.

Abstract

To study the role of B-cells in the regulation of glucagon secretion by glucose, the rat pancreas was perfused with 0.4 mmol/l diazoxide. Perfusate glucose was 5 mmol/l of a basal concentration, and then was decreased to 1 mmol/l, or was increased to 15 mmol/l. Insulin secretion was suppressed by diazoxide below the detectable level at each glucose concentration. Glucagon secretion was increased two-fold during the glucopenic perfusion without diazoxide, but was not changed at a low glucose concentration in the presence of diazoxide. During the glucose-excessive perfusion for 15 min, glucagon secretion was lowered from 0.69 +/- 0.17 pmol at 5 mmol/l glucose to 0.36 +/- 0.10 pmol at 15 mmol/l glucose (p < 0.05) without diazoxide, whereas that was inversely increased from 0.55 +/- 0.14 at 5 mmol/l glucose to 0.85 +/- 0.13 pmol at 15 mmol/l glucose (p < 0.05) in the presence of diazoxide. These results suggest that appropriate insulin secretion is necessary for the normal responses of glucagon secretion to hypoglycemia and hyperglycemia in the non-diabetic rat pancreas.

MeSH terms

  • Animals
  • Arginine / pharmacology
  • Diazoxide / pharmacology*
  • Glucagon / metabolism*
  • Glucose / administration & dosage*
  • Insulin / metabolism
  • Insulin Secretion
  • Male
  • Pancreas / drug effects*
  • Pancreas / metabolism*
  • Rats
  • Rats, Wistar

Substances

  • Insulin
  • Glucagon
  • Arginine
  • Glucose
  • Diazoxide