Electron microscopic demonstration of rat liver glycogen phosphorylase activity with iron (Fe++)

1974 ◽  
Vol 38 (4) ◽  
pp. 285-296 ◽  
Author(s):  
L. -A. Lindberg ◽  
A. Palkama
Keyword(s):  
Rat Liver ◽  
Glycogen Phosphorylase ◽  
Liver Glycogen ◽  
Phosphorylase Activity ◽  
Electron Microscopic ◽  
Microscopic Demonstration ◽  
Glycogen Phosphorylase Activity ◽  
Electron Microscopic Demonstration

Response of mouse liver glycogen cycle enzymes to endotoxin treatment

1976 ◽  
Vol 231 (4) ◽  
pp. 1285-1289 ◽  
Author(s):  
O Giger ◽  
RE McCallum
Keyword(s):  
Mouse Liver ◽  
Glycogen Phosphorylase ◽  
Glycogen Synthase ◽  
Lethal Dose ◽  
Active Form ◽  
Liver Glycogen ◽  
Phosphorylase Activity ◽  
Induced Changes ◽  
Glycogen Phosphorylase Activity ◽  
Glycogen Synthase Activity

The present study was undertaken to characterize endotoxin-induced changes in carbohydrate metabolism and more specifically, to determine the contribution of glycogenolysis to the loss of liver glycogen. Female ICR mice, fasted overnight, were injected with a median lethal dose (LD50, 9 mg/kg) of endotoxin extracted from Salmonella typhimurium strain SR-11. Glycogen synthase and glycogen phosphorylase activities were measured at 0.5 and 6 h after treatment. Endotoxin treatment did not alter total glycogen synthase activity, but the amount of enzyme present in the active form was significantly lower in endotoxic mice. There was no significant increase in glycogen phosphorylase activity in endotoxin-treated mice. Glycogen phosphorylase was activated to the same extent in control and endotoxic mice by decapitation or intravenous epinephrine (25 or 1 mug/kg). The results of this study indicate no significant increase in glycogen phosphorylase activity in endotoxic mice, contraindicating enhanced glycogenolysis as a mechanism for depletion of carbohydrate following endotoxin injection. Altered activation of glycogen synthase, however, may contribute to the loss of glycogen during endotoxemia.

Electron microscopical study of a cytosolic enzyme in unfixed cryostat sections: demonstration of glycogen phosphorylase activity in rat liver and heart tissue

1995 ◽  
Vol 27 (8) ◽  
pp. 609-614 ◽  
Author(s):  
Jacques P. M. Schellens ◽  
Helena Vreeling-Sindelárová ◽  
Rosier J. M. Van Den Munckhof ◽  
Wilma M. Frederiks
Keyword(s):  
Rat Liver ◽  
Glycogen Phosphorylase ◽  
Heart Tissue ◽  
Microscopical Study ◽  
Electron Microscopical Study ◽  
Phosphorylase Activity ◽  
Electron Microscopical ◽  
Glycogen Phosphorylase Activity ◽  
Cryostat Sections ◽  
Unfixed Cryostat

Cytochemical localization of glycogen phosphorylase activity in rat liver

1993 ◽  
Vol 51 ◽  
pp. 298-299
Author(s):  
John E. Michaels ◽  
Robert R. Cardell
Keyword(s):  
Rat Liver ◽  
Glycogen Phosphorylase ◽  
Periodic Acid ◽  
Glycogen Synthesis ◽  
Liver Glycogen ◽  
Periodic Acid Schiff ◽  
Cytochemical Localization ◽  
Key Enzyme ◽  
Staining Methods ◽  
Glycogen Phosphorylase Activity

Glycogen phosphorylase (GP) is a key enzyme in liver glycogen breakdown. GP activity is altered with its state of phosphorylation. In the current study, the intralobular distribution of GP activity was observed histochemically in frozen sections of rat liver during fasting and after stimulation of glycogen synthesis.Normal and adrenalectomized (ADX) rats were fasted overnight to reduce liver glycogen to minimal levels. Fasted ADX rats received 2 mg dexamethasone (DEX) 0-8 h prior to sacrifice to stimulate glycogen synthesis. Liver was removed, rapidly frozen in isopentane cooled in liquid nitrogen, then cryostat sectioned. In order to determine sites of GP activity, sections were incubated in medium that contained glucose 1-phosphate as substrate. Under the incubation conditions used, GP synthesized glycogen as the reaction product. Glycogen was identified by two staining methods: 1) iodine staining has been shown to be rather specific for newly synthesized glycogen produced during the histochemical procedure (Figs.1-6), whereas 2) periodic acid-Schiff (PAS) stained both native and nascent glycogen.

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