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Titolo:
Fish hepatocyte glycogen phosphorylase - a sensitive indicator for hormonal modulation
Autore:
Moon, TW; Busby, ER; Cooper, GA; Mommsen, TP;
Indirizzi:
Univ Ottawa, Dept Biol, Ottawa, ON K1N 6N5, Canada Univ Ottawa Ottawa ON Canada K1N 6N5 ept Biol, Ottawa, ON K1N 6N5, Canada Univ Victoria, Dept Biochem & Microbiol, Victoria, BC V8W 3P6, Canada UnivVictoria Victoria BC Canada V8W 3P6 ol, Victoria, BC V8W 3P6, Canada
Titolo Testata:
FISH PHYSIOLOGY AND BIOCHEMISTRY
fascicolo: 1, volume: 21, anno: 1999,
pagine: 15 - 24
SICI:
0920-1742(199907)21:1<15:FHGP-A>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
GLUCAGON-LIKE PEPTIDE; LIVER-GLYCOGEN; RAINBOW-TROUT; TELEOST HEPATOCYTES; SALMON GLUCAGON; EPINEPHRINE; STIMULATION; INSULIN; GLUCONEOGENESIS; METABOLISM;
Keywords:
caffeine; catecholamines; fish; glucose production; liver; method assay; phosphorylation; prostaglandin E-2;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: Moon, TW Univ Ottawa, Dept Biol, Ottawa, ON K1N 6N5, Canada Univ Ottawa Ottawa ON Canada K1N 6N5 Ottawa, ON K1N 6N5, Canada
Citazione:
T.W. Moon et al., "Fish hepatocyte glycogen phosphorylase - a sensitive indicator for hormonal modulation", FISH PHYS B, 21(1), 1999, pp. 15-24

Abstract

The absence of a reproducible method for the assay of glycogen phosphorylase (GPase) in isolated fish hepatocytes has made the interpretation of hormone-induced glycogenolysis data difficult. This study presents such an assay and demonstrates its sensitivity to hormonal activation. The enzyme is assayed in the reverse direction using glucose 1-phosphate (G1-P) and glycogen as substrates and uses standard methods for the quantification of the liberated inorganic phosphate. The assay is highly reproducible, sensitive, and provides an excellent means to follow small and rapid changes in enzyme phosphorylation status following the addition of hormones. We show for hepatocytes isolated from rockfish (Sebastes caurinus) and brown bullhead (Ameiurus (Ictalurus) nebulosus) that small concentrations of three model hormones, namely epinephrine (catfish), norepinephrine, and prostaglandin E-2 (rockfish), lead to the rapid, concentration and time-dependent conversion of existing GPase into the active GPase a form. Some of the enzyme seems to be impervious to hormonal activation, as the highest %GPase a never reaches 100%. We provide evidence that changes in enzyme phosphorylation status provide a better short-term insight into hormone-dependent activation than estimates of glucose or some other end products, that usually must accumulate for long periods before detection is possible. Our data also show that GPase in freshly isolated hepatocytes is already in an activated state and cells should be given a period of 'rest' for several hours before hormonal studies involving glycogen breakdown or the cAMP cascade are initiated.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/12/20 alle ore 17:56:23