title: Quantitative analysis of the pathways of glycogen repletion in periportal and perivenous hepatocytes in vivo.
abstract: In order to examine the pathways of hepatic glycogen repletion in the periportal and perivenous zones of the liver, [1-13C]glucose (99% enriched) was infused intraduodenally into conscious, 24-h fasted rats for 3 h. The liver was then quickly perfused in situ, and the cytoplasmic contents of the periportal and perivenous hepatocytes were selectively sampled by modification of the dual-digitonin-pulse technique (Quistorff, B., and Grunnet, N. (1987) Biochem. J. 243, 87-95). The 13C isotopic enrichment at each carbon position of the glucosyl units of hepatic glycogen was determined by 13C NMR and that of the C-1 position by gas chromatography-mass spectroscopy. From comparison of hepatic glycogen repleted by direct incorporation of plasma glucose (glucose----glucose-6-P----glucose-1-P----UDP-glucose----glycogen) was calculated to be 29% in the periportal zone and 35% in the perivenous zone, assuming equal glycogen synthetic rates within the two zones. Thus, the majority of glycogen is derived by an indirect route (glucose--------3-carbon unit--------glucose --------UDP-glucose--------glycogen) in both the periportal zone and in the perivenous zone. In conclusion, in a 24-h fasted rat there does not appear to be a major difference between the periportal and perivenous hepatocytes in the percent of glycogen synthesized by the direct pathway following a glucose load.
authors.affiliation: Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510.
authors.forename: G W
authors.initials: GW
authors.lastname: Cline
authors.forename: G I
authors.initials: GI
authors.lastname: Shulman
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D001786:Blood Glucose; D008112:Liver Glycogen; D007770:L-Lactate Dehydrogenase; D005974:Glutamate-Ammonia Ligase