Glucose Oxidation (14-CO₂ Production) and Insulin Secretion by Pancreatic Islets Isolated from Hyperglycemic and Normoglycemic Rats

Pancreatic islets from glucose-infused rats retained a “memory” of the hyperglycemic environment, (a) They oxidized (14-CO₂ production) glucose-U-14-C and glucose-6-14-C at rates three to four times higher than islets from normoglycemic rats. Inhibitors of insulin secretion and synthesis did not affect the rates of 14-C₂ production. In contrast, ouabain (1 mM) decreased glucose oxidation by nearly 50 per cent, (b) They secreted insulin in vitro at rates similar to those of islets of control rats, in spite of the heavy degranulation of their beta cells.