FIG. 1.

Schematic representation of the experimental procedures. A: Basal state. At t = 0 min, a continuous intracerebroventricular infusion of vehicle or tolbutamide was started and maintained throughout the entire experiment. At t = 30 min, a primed, continuous intravenous infusion of [¹⁴C]glucose was initiated and maintained for the remainder of the experiment. At t = 90 min, an intravenous bolus of 2-[³H]DG was administered. At t = 0, 100, 110, and 120 min, blood samples were obtained, and at t = 120 min the animals were killed and organs were harvested. B: Hyperinsulinemic-euglycemic state. At t = 0 min, a continuous intracerebroventricular infusion of vehicle or tolbutamide was started and maintained throughout the entire experiment. At t = 30 min, a hyperinsulinemic-euglycemic clamp was started by primed, continuous infusion of insulin together with [¹⁴C]glucose. A variable infusion of 12.5% glucose was used to maintain euglycemia. At t = 90 min, an intravenous bolus of 2-[³H]DG was administered. At t = 0, 100, 110, and 120 min, blood samples were obtained, and at t = 120 min the animals were killed and organs harvested.