Some peculiarities of the glucoregulatory response to glucose infusion in the rat

Abstract

The glucoregulatory response to the i.v. infusion of different doses of glucose and glucose plus insulin was studied in anesthetized rats by using the primed constant infusion of glucose-2-3H. Infusion of glucose at the rate of 10 mg/kg/min induced a rise of about 100% in blood glucose, while the hepatic release of glucose showed only a small and transient decrease. A proportional increase of glycemia and glucose utilization (Rd) was observed without any appreciable change in the metabolic clearance rate (MCR) of glucose; a two-fold increase in plasma insulin was recorded at all times. In the group of rats receiving 20 mg/kg/min of glucose, changes in the above parameters were slightly greater; MCR showed a moderate increment in spite of the six-fold rise of plasma insulin. Finally, the influsion of large doses of insulin together with 20 mg/kg/min of glucose resulted in complete cessation of glucose release by the liver and in a remarkable increase of Rd and MCR. These results suggest a poor adaptability of the glucoregulatory system of the rat in response to glucose infusion as compared to other mammalian species.

Monitoring acute metabolic changes in the liver and kidneys induced by fructose and glucose using hyperpolarized [2‐13C]dihydroxyacetone

“…Because of the tight metabolic regulation associated with glucokinase, it is highly likely that hepatic glucose uptake was well controlled, and therefore glycolysis/GNG was largely unperturbed. Additionally, it has been reported that the glucose regulatory system of rats is less responsive to an increase in the circulating glucose than other animal species 23 . The lack of variability in the measured parameters using the glucose challenge serves as an excellent control for the fructose challenge.…”