The effects of minimal increments in plasma insulin concentrations on hepatic glucose production and glucose uptake, skeletal muscle net glycogen synthesis and glycogenolysis, glycogen synthase and phosphorylase activity, glucose-6-phosphate and uridinediphosphoglucose (UDPG) concentrations were examined in 24-h and in 6-h fasted conscious rats. Insulin was infused for 120 min at rates of 1.5, ...

Citation: Chen Y, Du T, Peng L, Gibbs ME and Hertz L (2016) Sequential Astrocytic 5-HT2B Receptor Stimulation, [Ca ]i Regulation, Glycogenolysis, Glutamate Synthesis, and K Homeostasis are Similar but Not Identical in Learning and Mood Regulation. Front. Integr. Neurosci. 9:67. doi: 10.3389/fnint.2015.00067 Sequential Astrocytic 5-HT2B Receptor Stimulation, [Ca]i Regulation, Glycogenolysis, Glu...

Catecholamines increased guanosine 3':5'-monophosphate (cyclic GMP) accumulation by isolated rat liver cells. The increases in cyclic GMP due to 1.5 muM epinephrine, isoproterenol, or phenylephrine were blocked by phenoxybenzamine but not by propranolol. The possibility that cyclic GMP is involved in the glycogenolytic action of catecholamines seems unlikely since cyclic GMP accumulation is als...

Leptin and insulin share some hypothalamic signaling molecules, but their central administration induces different effects on hepatic glucose fluxes. Acute insulin infusion in the third cerebral ventricle inhibits endogenous glucose production (GP), whereas acute leptin infusion stimulates gluconeogenesis but does not alter GP because of a compensatory decrease in glycogenolysis. Because melano...

Glucagon and alpha-adrenergic-induced glycogenolysis is realized via the agonist/adenylyl cyclase/cAMP/protein kinase signaling pathway or via the activation of phosphorylase kinase by the mobilized calcium that supports the inhibition of glycogen synthase, respectively. The role of nitric oxide (NO) in this process has not been extensively studied. The present work was directed to the question...

Improvement of glucose metabolism after bariatric surgery appears to be from the composite effect of the alterations in multiple circulating gut hormone concentrations. However, their individual effect on glucose metabolism during different conditions is not clear. The objective of this study was to determine whether ghrelin has an impact on glycogenolysis, gluconeogenesis, and insulin sensitiv...

Net hepatic glycogenolysis and gluconeogenesis were examined in normal ( n = 4) and cirrhotic ( n = 8) subjects using two independent methods [13C nuclear magnetic resonance spectroscopy (NMR) and a2H2O method]. Rates of net hepatic glycogenolysis were calculated by the change in hepatic glycogen content before (∼11:00 PM) and after (∼7:00 AM) an overnight fast using13C NMR and magnetic resonan...

Glycogenolysis was studied in glycogen-rich perfused livers in which glycogen phosphorylase was fully converted into the a form by exposure of the livers to dibutyryl cyclic AMP. We monitored intracellular Pi by 31P n.m.r. Perfusion with Pi-free medium during 30 min caused a progressive decrease of the Pi signal to 50% of its initial value. In contrast, exposure of the livers to KCN and/or 2,4-...

1. The glycogen formed in the livers of adult rats was labelled by injection of [1-14C] galactose soon after initiation of re-feeding after starvation. The rats were anaesthetized 4h later and glycogenolysis was induced by giving them a mixture of glucagon and insulin. In confirmation of previous work [Devos & Hers (1979) Eur J. Biochem. 99, 161-167],, there was a delay in degradation of the la...

The utilization of glycogen by skeletal muscle was, at one time, one of the central problems of biochemistry. Attention focused on the most dramatic property of the system: the very rapid glycogenolysis that occurs synchronously with muscle contraction. This phenomenon now has a generally accepted explanation : the increase in Ca2+ that induces muscle contraction also activates phosphorylase ki...