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Title: On the role of calcium ions in the regulation of glycogenolysis in mouse brain cortical slices
Authors: Ververken, Dirk
Van Veldhoven, Paul P
Proost, Catheline
Carton, Herwig ×
De Wulf, H #
Issue Date: May-1982
Series Title: Journal of Neurochemistry vol:38 issue:5 pages:1286-95
Abstract: Using mouse brain cortical slices, we investigated the relative roles of cyclic AMP and of calcium ions as the intracellular messengers for the activation of glycogen phosphorylase (EC 2.4.1.1; alpha-1,4-glucan:orthophosphate glucosyltransferase) induced by noradrenaline and by depolarization. Activation of phosphorylase by 100 microM noradrenaline is mediated by beta-adrenergic receptors and does not require the copresence of adenosine. The role of the concomitant small increase in cyclic AMP is questioned. Short-term treatment with EGTA or LaCl3 abolishes the noradrenaline activation of phosphorylase, pointing to a critical role of extracellular calcium. Depolarization by 25 mM K+ or 100 microM veratridine produces a rapid and large (fourfold) activation of phosphorylase. Only veratridine increases the cyclic AMP levels; exogenous adenosine deaminase essentially blocks this cyclic AMP accumulation but not the phosphorylase activation. A half-maximal activation of phosphorylase occurs at about 12 mM K+. Addition of EGTA or LaCl3 reduces the effect of both depolarizations to a slight and transient activation of phosphorylase. These results indicate that activation of glycogen phosphorylase by K+ or veratridine occurs by a cyclic AMP-independent and calcium-dependent mechanism. The calcium dependency of brain phosphorylase kinase renders this kinase the prime target enzyme for regulation of glycogenolysis by calcium ions.
ISSN: 0022-3042
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Pharmacology Section (-)
Faculty of Medicine - miscellaneous
Laboratory of Lipid Biochemistry and Protein Interactions
× corresponding author
# (joint) last author

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