Studies of Glucose Production in Sheep Using [6-3H]Glucose and [U-14C] Glucose

Abstract

Simultaneous primed-continuous intravenous infusions of [6-³H]glucose and [U-¹⁴C]glucose were performed on 13 fed, 4 fasted, and 4 dexamethasone-treated sheep. In 10 of the experiments on fed sheep, glucagon or insulin was infused intraportally for 2 h after control values were obtained. The ³H-labeled glucose gave glucose production values that were only 4.4 ± 0.5, 5.4 ± 1.0, and 5.8 ± 0.8% higher than ¹⁴C-labeled glucose in the normal fed, fasted, and dexamethasone-treated sheep, respectively. Glucagon or insulin infusions did not significantly alter this recycling. It is concluded that a recycling of glucose carbon through metabolic intermediates is minimal in the sheep as compared with other species and also that it is not significantly altered by fasting or by hormones that affect glucose production.