Sulfonylureas activate glycogen phosphorylase and increase cytosolic free-Ca2+ levels in isolated rat hepatocytes

Without causing significant changes in cellular levels of cyclic adenosine monophosphate (cAMP), the addition of either glibenclamide or gliquidone to isolated rat hepatocytes caused a transient dose- and Ca(2+)-dependent activation of glycogen phosphorylase. The calculated concentrations correspond...

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Published inMetabolism, clinical and experimental Vol. 42; no. 5; p. 624
Main Authors López-Alarcón, L, Melián, E, Muñoz-Alonso, M J, Guijarro, C, Boscá, L, Felíu, J E
Format Journal Article
LanguageEnglish
Published United States 01.05.1993
Subjects
Animals
Calcium - metabolism
Cell Separation
Cytosol - metabolism
Enzyme Activation
Glyburide - pharmacology
Ions
Liver - cytology
Liver - metabolism
Phosphorylases - metabolism
Rats
Sulfonylurea Compounds - pharmacology
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Summary:Without causing significant changes in cellular levels of cyclic adenosine monophosphate (cAMP), the addition of either glibenclamide or gliquidone to isolated rat hepatocytes caused a transient dose- and Ca(2+)-dependent activation of glycogen phosphorylase. The calculated concentrations corresponding to half-maximal activation were 5 and 2 mumol/L, respectively. In connection with this, it was observed that glibenclamide provoked a dose-dependent increase in cytosolic free-calcium concentration ([Ca2+]i) in Fura-2-loaded hepatocytes. Moreover, the presence of glibenclamide in the incubation medium accelerated the rate of Ca2+ uptake by Ca(2+)-depleted hepatocytes. These findings suggest that an increase in [Ca2+]i could mediate some of the effects of sulfonylureas in liver metabolism.
ISSN:0026-0495
DOI:10.1016/0026-0495(93)90222-a