Effects of carbohydrates on the oxygen consumption of isolated pancreatic islets of mice.

Abstract

In studies of the carbohydrate metabolism of mammalian pancreatic β cells, Cartesian divers were used for analyses of the oxygen consumption of isolated surviving islets of Langerhans from obese-hyperglycemic mice. When single islets (dry weight 1–10 μg) were incubated in Krebs-Ringer phosphate buffer at 37 C, the islet cells respired at a constant rate for several hours. A rapid and pronounced elevation of the respiratory rate was observed, when the incubation medium was supplemented with D-glucose in a concentration of 3 mg/ml. The oxygen uptake increased with glucose concentration in the range 0.5–3 mg/ml. A smaller degree of stimulation of the respiratory rate was obtained with D-mannose and D-fructose. D-Galactose and 2-deoxy-D-glucose had no obvious effects on the endogenous respiration of the islet cells, whereas a slightly inhibitory effect was noted with D-mannoheptulose. In addition, the latter carbohydrate almost completely blocked the effect of glucose on the islet respiration and strongly inh...