title: Hepatic autoregulation: response of glucose production and gluconeogenesis to increased glycogenolysis.
abstract: The effect of increased glycogenolysis, simulated by galactose's conversion to glucose, on the contribution of gluconeogenesis (GNG) to hepatic glucose production (GP) was determined. The conversion of galactose to glucose is by the same pathway as glycogen's conversion to glucose, i.e., glucose 1-phosphate --> glucose 6-phosphate --> glucose. Healthy men (n = 7) were fasted for 44 h. At 40 h, hepatic glycogen stores were depleted. GNG then contributed approximately 90% to a GP of approximately 8 micromol.kg(-1).min(-1). Galactose, 9 g/h, was infused over the next 4 h. The contribution of GNG to GP declined from approximately 90% to 65%, i.e., by approximately 2 micromol.kg(-1).min(-1). The rate of galactose conversion to blood glucose, measured by labeling the infused galactose with [1-(2)H]galactose (n = 4), was also approximately 2 micromol.kg(-1).min(-1). The 41st h GP rose by approximately 1.5 micromol.kg(-1).min(-1) and then returned to approximately 9 micromol.kg(-1).min(-1), while plasma glucose concentration increased from approximately 4.5 to 5.3 mM, accompanied by a rise in plasma insulin concentration. Over 50% of the galactose infused was accounted for in blood glucose and hepatic glycogen formation. Thus an increase in the rate of GP via the glycogenolytic pathway resulted in a concomitant decrease in the rate of GP via GNG. While the compensatory response to the galactose administration was not complete, since GP increased, hepatic autoregulation is operative in healthy humans during prolonged fasting.
authors.affiliation: Medical Endocrinological Department, Odense University Hospital, Odense, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Staehr
authors.forename: Ole
authors.initials: O
authors.lastname: Hother-Nielsen
authors.forename: Henning
authors.initials: H
authors.lastname: Beck-Nielsen
authors.forename: Michael
authors.initials: M
authors.lastname: Roden
authors.forename: Harald
authors.initials: H
authors.lastname: Stingl
authors.forename: Jens J
authors.initials: JJ
authors.lastname: Holst
authors.forename: Paul K
authors.initials: PK
authors.lastname: Jones
authors.forename: Visvanathan
authors.initials: V
authors.lastname: Chandramouli
authors.forename: Bernard R
authors.initials: BR
authors.lastname: Landau
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002097:C-Reactive Protein / Q000378:metabolism; D005215:Fasting / Q000097:blood / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D005934:Glucagon / Q000097:blood; D005943:Gluconeogenesis / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D050261:Glycogenolysis / Q000502:physiology*; D006801:Humans; D007328:Insulin / Q000097:blood; D008099:Liver / Q000378:metabolism*; D008297:Male; D008875:Middle Aged
chemical_list: D001786:Blood Glucose; D007328:Insulin; D002097:C-Reactive Protein; D005934:Glucagon; D005947:Glucose; D005690:Galactose