title: Heterogeneity of glycogen synthesis upon refeeding following starvation.
abstract: 1. Starvation of rats for 40 hr decreased the body weight, liver weight and blood glucose concentration. The hepatic and skeletal muscle glycogen concentrations were decreased by 95% (from 410 mumol/g tissue to 16 mumol/g tissue) and 55% (from 40 mumol/g tissue to 18.5 mumol/g tissue), respectively. 2. Fine structural analysis of glycogen purified from the liver and skeletal muscle of starved rats suggested that the glycogenolysis included a lysosomal component, in addition to the conventional phosphorolytic pathway. In support of this the hepatic acid alpha-glucosidase activity increased 1.8-fold following starvation. 3. Refeeding resulted in liver glycogen synthesis at a linear rate of 40 mumol/g tissue per hr over the first 13 hr of refeeding. The hepatic glycogen store were replenished by 8 hr of refeeding, but synthesis continued and the hepatic glycogen content peaked at 24 hr (approximately 670 mumol/g tissue). 4. Refeeding resulted in skeletal muscle glycogen synthesis at an initial rate of 40 mumol/g tissue per hr. The muscle glycogen store was replenished by 30 min of refeeding, but synthesis continued and the glycogen content peaked at 13 hr (approximately 50 mumol/g tissue). 5. Both liver and skeletal muscle glycogen synthesis were inhomogeneous with respect to molecular size; high molecular weight glycogen was initially synthesised at a faster rate than low molecular weight glycogen. These observations support suggestions that there is more than a single site of glycogen synthesis.
authors.affiliation: Department of Biochemistry, University of Auckland, New Zealand.
authors.forename: P C
authors.initials: PC
authors.lastname: Calder
authors.forename: R
authors.initials: R
authors.lastname: Geddes
mesh_terms: D000818:Animals; D001835:Body Weight; D005502:Food; D006003:Glycogen / Q000096:biosynthesis* / Q000737:chemistry; D007700:Kinetics; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism; D008297:Male; D008970:Molecular Weight; D009132:Muscles / Q000378:metabolism; D009929:Organ Size; D051381:Rats; D011919:Rats, Inbred Strains; D013217:Starvation
chemical_list: D006003:Glycogen