FIG. 2.

Intraportal 10-min insulin delivery protocol in rats (rat protocol 3). A and B: Schematic representation of portal vein insulin infusion procedure in rats. Rats were anesthetized and indwelling catheters were placed into the mesenteric vein, jugular vein, and carotid artery. Rats received a constant intravenous infusion of somatostatin (10 μg/kg/min) for 30 min to inhibit endogenous insulin release. Insulin was infused intraportally at the rate of 70 pmol/kg/min either in a typical pulsatile pattern, in a same-rate constant insulin infusion, or as an insulin infusion selected to reproduce that observed in patients with evolving diabetes (∼50% decrease in pulse mass). Sequential hepatic biopsies were obtained at 0, 2, 6, and 10 min after the start of insulin infusion. Body weight (C), plasma glucose (D), and free fatty acid (E) levels were not significantly different after the three modes of insulin delivery. Data are mean ± SE.