Fig. 2.

Arterial plasma glucose levels (A), glucose infusion rates (B), and changes in net hepatic glucose (C), and [3-³H]glucose balance (D) before (control) and after drug treatment (Test Period I) and subsequent increase of plasma glucagon (Test Period II) in 18-h fasted conscious dogs. The animals received intragastric bolus injection of vehicle or GPI (10 mg/kg) at 0 min, continuous infusion of metformin, or vehicle into the portal vein (0.15 mg · kg⁻¹ · min⁻¹) from 0 min, and a 4-fold increase in intraportal glucagon brought about from 90 min. Values are means ± S.E. for five experiments. *, significantly different from the corresponding value in vehicle group (P < 0.05). †, significantly different from the control period with the same group (P < 0.05). ‡, significantly different from the corresponding value at 90 min in the Test Period I with the same group (P < 0.05).