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Titolo:
ABSENCE OF GLYCOGEN CYCLING IN CULTURED RAT HEPATOCYTES
Autore:
GRUNNET N; JENSEN S; DICH J;
Indirizzi:
UNIV COPENHAGEN,PANUM INST,PHARMABIOTEC RES CTR,DEPT MED BIOCHEM & GENET COPENHAGEN DENMARK
Titolo Testata:
Archives of biochemistry and biophysics
fascicolo: 1, volume: 309, anno: 1994,
pagine: 18 - 23
SICI:
0003-9861(1994)309:1<18:AOGCIC>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
LONG-TERM CULTURE; LIVER-GLYCOGEN; GLUCOSE; DEGRADATION; PROSTAGLANDIN-D2; STIMULATION; GLYCOLYSIS; INSULIN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
27
Recensione:
Indirizzi per estratti:
Citazione:
N. Grunnet et al., "ABSENCE OF GLYCOGEN CYCLING IN CULTURED RAT HEPATOCYTES", Archives of biochemistry and biophysics, 309(1), 1994, pp. 18-23

Abstract

Glycogen synthesis and degradation were studied in cultured rat hepatocytes prelabeled by incubation with [C-14]glucose or [C-14]galactose. During prelabeling about 75% of the accumulated glycogen was synthesized from glucose and about 25% from gluconeogenic precursors. Following the labeling period, glycogen synthesis and degradation were estimated at 5 and 12.5 mM glucose and varying concentrations of insulin and glucagon. At 12.5 mM glucose and 10 nM insulin the accumulation of glycogen was comparable to in vivo values, whereas the level of radioactivity in prelabeled glycogen remained constant. Further addition of 0.1nM glucagon resulted in constant values of both content and radioactivity of glycogen. Increasing the concentration of glucagon to 10 nM resulted in a parallel decrease of content and radioactivity in glycogen. At 5 mM glucose, 10 nM insulin, and 0.1 nM glucagon both the contentand the radioactivity of glycogen were constant, whereas addition of 10 nM glucagon resulted in a parallel decrease of content and radioactivity of glycogen, which was 64% higher than that observed with 12.5 mM glucose. In the absence of insulin, prostaglandin D-2 had effects similar to those of 10 nM glucagon, whereas no effects was observed in the presence of insulin. From these results and from calculated rates of glucose B-phosphate formation, it is concluded that the rate of glycogen degradation is less than 10% of the rate of synthesis under conditions favoring glycogen accumulation, At conditions favoring glycogen degradation (10 nM insulin plus 10 nM glucagon or prostaglandin in theabsence of insulin) no synthesis could be detected. Results from cells prelabeled with [C-14]galactose suggested that glycogen degradation is not an absolutely ordered process, but that some random degradationtakes place. (C) 1994 Academic Press, Inc.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 12/07/20 alle ore 09:07:49