Important role of the hepatic vagus nerve in glucose uptake and productionby the liver

We examined the role of the hepatic vagus nerve in hepatic and peripheral g lucose metabolism. To assess endogenous glucose production (EGP), hepatic u ptake of first-pass glucose infused intraportally (HGU), and the metabolic clearance rate of glucose (MCR), rats were subjected to hepatic vagotomy (H V, n = 7) or sham operation (SH, n = 8), after 10 days, they were then subj ected to a euglycemic-hyperinsulinemic clamp together with a portal glucose load in the 24-hour fasting state. Metabolic parameters were determined by the dual-tracer method using stable isotopes. During the experiment, [6,6- H-2(2)]glucose was continuously infused into the peripheral vein. To mainta in euglycemia (4.5 mmol/L), insulin (54 pmol.kg(-1).min(-1)) and glucose we re infused peripherally after the 90-minute tracer equilibration and 30-min ute basal periods, and glucose containing 5% enriched [U-C-13]glucose was i nfused intraportally (50 mu mol.kg(-1).min(-1)) for 120 minutes (clamp peri od). EGP was significantly higher in HV rats versus SH rats during the basa l period (64.3 +/- 7.6 v 43.6 +/- 5.3 mu mol.kg(-1).min(-1), P < .005) and was comparable to EGP in SH rats during the clamp period (9.3 +/- 21.5 v 1. 1 +/- 11.7 mu mol.kg(-1.)min(-1)). HGU was reduced in HV rats compared with SH rats during portal glucose infusion (5.9 +/- 2.4 v 10.1 +/- 3.2 mu mol. kg(-1).min(-1)). The MCR in HV rats was significantly higher than in SH rat s in the basal period (11.0 +/- 2.0 v 7.9 +/- 0.8 mL.kg(-1).min(-1), P < .0 1) and was comparable to the MCR in SH rats during the clamp period (41.9 /- 10.0 and 36.6 +/- 5.7 mL.kg(-1).min(-1)). We conclude that innervation o f the hepatic vagus nerve is important for the regulation of hepatic glucos e production in the postabsorptive state and HGU in the postprandial state. Copyright (C) 2000 by W.B. Saunders Company.