title: Inactivation of the AMP-activated protein kinase by glucose in cardiac myocytes: a role for the pentose phosphate pathway.
abstract: Incubation of adult rat cardiac myocytes with increasing glucose concentrations decreased phosphorylation (αThr172) and activity of AMPK (AMP-activated protein kinase). The effect could be demonstrated without measurable changes in adenine nucleotide contents. The glucose effect was additive to the decrease in AMPK activity caused by insulin, was attenuated by adrenaline, was not mimicked by glucose analogues, lactate or pyruvate and was not due to changes in myocyte glycogen content. AMPK activity was decreased by xylitol and PMS (phenazine methosulfate) and was increased by the glucose-6-phosphate dehydrogenase inhibitor DHEA (dehydroepiandrosterone) and by thiamine. PMS and DHEA respectively, increased and decreased CO2 formation by the PPP (pentose phosphate pathway). AMPK activity was inversely related to the myocyte content of Xu5P (xylulose 5-phosphate), an intermediate of the non-oxidative arm of the PPP. Endothall, an inhibitor of PP2A (protein phosphatase 2A), abolished the glucose effect on AMPK activity. Further studies are needed to define the 'active component' that mediates the glucose effect and whether its site of action is PP2A.
authors: Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K.
authors: Ikhlass
authors: I
authors: Tabidi
authors: David
authors: D
authors: Saggerson
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D003687:Dehydroepiandrosterone / Q000494:pharmacology; D003998:Dicarboxylic Acids / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism / Q000502:physiology*; D007328:Insulin / Q000502:physiology; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008773:Methylphenazonium Methosulfate / Q000494:pharmacology; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010084:Oxidation-Reduction; D010427:Pentose Phosphate Pathway; D010766:Phosphorylation; D054648:Protein Phosphatase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley; D013831:Thiamine / Q000494:pharmacology
chemical_list: D003998:Dicarboxylic Acids; D007328:Insulin; D007527:Isoenzymes; D002245:Carbon Dioxide; C100030:endothall; D008773:Methylphenazonium Methosulfate; D003687:Dehydroepiandrosterone; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases; D054648:Protein Phosphatase 2; D000103:Acetyl-CoA Carboxylase; D005947:Glucose; D013831:Thiamine