Fig. 3.

Net hepatic gluconeogenesis precursor uptake (A) before (control) and after drug treatment (Test Period I) and subsequent increase of plasma glucagon (Test Period II) and changes in net hepatic gluconeogenesis precursor uptake from that in the control period (B) 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. The rate was obtained by summation of net hepatic uptake rates of lactate, glycerol, pyruvate, and all gluconeogenic amino acids. Lactate uptake was considered as zero when lactate was released by the liver. Values are means ± S.E. for five experiments. *, significantly different from the corresponding value in the vehicle group (P < 0.05). †, significantly different from the control period (P < 0.05). ‡, significantly different from the corresponding value at 90 min in the Test Period I with the same group (P < 0.05).