Figure 1.

Study design. Eleven dogs underwent two insulin and glucose clamp periods, beginning at 0 min. Clamp conditions were as described in the figure. In the INS group, insulin was infused intraportally at a rate (mU ⋅ kg⁻¹ ⋅ min⁻¹) of 2.1 from 0 to 30 min, 2.4 from 30 to 60 min, and 1.5 from 60 to 240 min. At 240 min, the first clamp ceased, and a primed continuous infusion of [³H]glucose began. After a 90-min equilibration period (240–330 min), there was a 30-min period of sampling under nonclamp conditions. These 11 dogs subsequently underwent an HIHG clamp in the presence of the portal glucose signal from 360 to 600 min (clamp 2). Hepatic tissue was collected from these dogs at 600 min. In addition to the dogs that underwent both clamps, two dogs that received the INS treatment and two that received the GLC treatment were euthanized at 360 min, with tissue biopsy samples obtained at that time to provide an indication of glycogen stores, enzyme activities, and protein expression before the start of clamp 2. IV, intravenous.