scholarly journals Glycogenolysis in liver of phosphorylase kinase-deficient rats during liver perfusion and ischaemia

1983 ◽  
Vol 214 (2) ◽  
pp. 645-648 ◽  
Author(s):  
G Lutaya ◽  
R J Sharma ◽  
J R Griffiths
Keyword(s):  
Liver Perfusion ◽  
Liver Glycogen ◽  
Alpha Activity ◽  
Transient Increase ◽  
Phosphorylase Kinase ◽  
Phosphorylase Activity ◽  
Main Determinant ◽  
Rat Livers

Liver glycogen degradation and phosphorylase activity were measured in normal and phosphorylase kinase-deficient (gsd/gsd) rats. During perfusion or ischaemia, gsd/gsd-rat livers showed a brisk glycogenolysis. There was also a small (1.9-fold) but significant transient increase in their phosphorylase alpha activity during ischaemia, despite their phosphorylase b kinase deficiency; it seems unlikely, however, that this was the main determinant of the glycogenolysis.

Glycogen Phosphorylase in the Fat Body of Two Cockroach Species, Periplaneta americana and Nauphoeta cinerea: Isolation, Partial Characterization of Three Forms and Activation by Hypertrehalosaemic Hormones

1991 ◽  
Vol 46 (1-2) ◽  
pp. 149-162 ◽  
Author(s):  
Gerd Gäde
Keyword(s):  
Anion Exchange ◽  
Glycogen Phosphorylase ◽  
Periplaneta Americana ◽  
Fat Body ◽  
Phosphorylase Kinase ◽  
Phosphorylase Activity ◽  
Strong Inhibitor ◽  
Nauphoeta Cinerea ◽  
Crude Extracts ◽  
Fat Bodies

The presence of endogenous phosphorylase kinase and phosphorylase phosphatase in crude extracts of fat bodies from the cockroaches Nauphoeta cinerea and Periplaneta americana is demonstrated in vitro by activation/inactivation of glycogen phosphorylase under appropriate conditions. Fractionation of fat body extracts of both cockroach species on an anion-exchange medium results in the elution of three peaks with phosphorylase activity. According to their AMP dependency these activity peaks are designated as phosphorylase b (inactive without AMP), phosphorylase ab (active without AMP, but several stimulated with AMP) and phosphorylase a (active without AMP). It is shown chromatographically that incubating crude extracts of fat bodies from both cockroaches, under conditions where the phosphorylase kinase is active, results in all phosphorylase b being converted to the ab- or a-form , whereas under conditions where the phosphorylase phosphatase is active all phophorylase a is converted to the ab- or b-form . Endogenous phosphorylase kinase of N. cinerea crude fat body extract can convert vertebrate phosphorylase b into the a-form , and, conversely, vertebrate muscle p hosphorylase kinase and phosphorylase phosphatase, respectively, are able to convert partially purified N. cinerea phosphorylase aborb and the ab- und a-form , respectively. In resting cockroaches most of the phosphorylase activity resides in the b-form and only a small fraction (10% ) in the a-form , whereas between 26% (N . cinerea) and 35% (P. americana) occurs in the ab-form . Injection of endogenous hypertrehalosaemic peptides into N. cinerea (the decapeptide Bld-HrTH ) or P. americana (the two octapeptides Pea-CAH -I and II) causes interconversion of phosphorylase; after injection, mainly (60% ) phosphorylase a is present, while 25% and 15% exists in the ab- und b-form , respectively. Purification of the three phosphorylase forms from N. cinerea is achieved by anion-exchange chromatography on DEAE-Sephacel followed by affinity chromatography on AMP-Sepharose. The final specific activities are 2.1, 6.9 and 27.2 U /mg protein for the a-, ab- und b-form . The molecular mass of the active molecules on gel filtration is between 173,000 and 177,000, and SDS gel electrophoresis reveals a subunit mass of 87,100, suggesting a homodimeric structure for all three form s. Kinetic studies show hyperbolic saturation curves for the substrates glycogen and Pi respectively, with Kᴍ-values of 0.021, 0.019 and 0.073% for glycogen and 8.3, 6.3 and 17.9 mᴍ for Pi (a-, ab- and b-form ). Phosphorylase a exhibits a more or less hyperbolic response to AMP and needs 70 |iM A M P for m axim al stim ulation. The kinetics for the ab- and b-form s are sigm oidal and maximal activities are displayed at about 3 mᴍ (half-maximum activation as calculated from Hill plots are 55 and 280 μᴍ for the ab- und b-form , respectively). Caffeine is a strong inhibitor of the b-form , but has only a slight inhibiting effect (10 -20 % ) on the ab- and a-form in the presence of AMP.

scholarly journals Regulation of rat liver glycogen synthase. Roles of Ca2+, phosphorylase kinase, and phosphorylase a.

1983 ◽  
Vol 258 (9) ◽  
pp. 5490-5497
Author(s):  
W G Strickland ◽  
M Imazu ◽  
T D Chrisman ◽  
J H Exton
Keyword(s):  
Rat Liver ◽  
Glycogen Synthase ◽  
Liver Glycogen ◽  
Phosphorylase Kinase

Temporal patterns of tissue glycogen, glucose, and glycogen phosphorylase activity prior to hibernation in freeze-tolerant chorus frogs, Pseudacris triseriata

2008 ◽  
Vol 86 (10) ◽  
pp. 1095-1100 ◽  
Author(s):  
Steve C. Dinsmore ◽  
David L. Swanson
Keyword(s):  
Glycogen Phosphorylase ◽  
Threshold Level ◽  
Liver Glycogen ◽  
Critical Threshold ◽  
Hepatic Glycogen ◽  
Phosphorylase Activity ◽  
Continuous Increase ◽  
Glycogen Accumulation ◽  
Chorus Frogs ◽  
Glycogen Stores

Freezing survival may differ among winters in chorus frogs ( Pseudacris triseriata (Wied-Neuwied, 1838)), and low freezing survival is associated with low hepatic glycogen stores. The pattern of prehibernation liver glycogen accumulation in chorus frogs is unknown. Frogs might accumulate hepatic glycogen stores until a threshold level sufficient for winter survival is attained, after which frogs enter hibernation (critical threshold hypothesis). According to this model, frogs active late in the season should only be those with low hepatic glycogen stores. Alternatively, hepatic glycogen levels might continue to increase throughout the fall as long as frogs remain active (continuous increase hypothesis). We tested these hypotheses by measuring liver and leg muscle glycogen, glucose, and glycogen phosphorylase activities in chorus frogs throughout the fall prehibernation period in southeastern South Dakota. Hepatic glycogen levels were significantly related to date and increased throughout the fall period, consistent with the continuous increase hypothesis. This suggests that hepatic glycogen levels do not serve as a cue for entrance into hibernation. Liver phosphorylase activity did not vary significantly with progression of the fall season and activity was lower than in winter, suggesting that the winter increment of phosphorylase activity requires some stimulus during hibernation (e.g., low temperatures).

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.

Initial stages of intermediary glucose catabolism in the hibernator and nonhibernator

1961 ◽  
Vol 201 (2) ◽  
pp. 217-223 ◽  
Author(s):  
John P. Hannon ◽  
David A. Vaughan
Keyword(s):  
Dehydrogenase Activity ◽  
Species Differences ◽  
Glycogen Synthesis ◽  
Liver Glycogen ◽  
The Arctic ◽  
Moderate Increase ◽  
Sharp Reduction ◽  
Phosphorylase Activity ◽  
Complete Obliteration ◽  
Glucose 6 Phosphate Dehydrogenase

In the Arctic ground squirrel, hibernation caused a marked hypoglycemia and a twofold increase in myocardial and skeletal muscle glycogen, but had no effect on liver glycogen. When assayed at 30 C, hibernation led to a moderate increase in the glucokinase and glucose-6-phosphate dehydrogenase activity of the myocardium. Finally, it also caused a sharp reduction in the glucose-6-phosphate dehydrogenase activity and almost a complete obliteration of phosphorylase activity in the liver. Between species, the laboratory rat exhibited about 50% more myocardial glucose-6-phosphate dehydrogenase and about twice as much phosphorylase as the myocardium of the awake squirrel. The liver of the awake squirrel had about 50% more glucose-6-phosphatase, about 60% more phosphorylase, about twice as much glucokinase, and about four times as much glucose-6-phosphatase as the liver of the rat. A number of correlated enzyme activities were observed. The mechanisms underlying the hypoglycemia and net glycogen synthesis of hibernation and the species differences in carbohydrate metabolism and lipogenic capacity are discussed.

Liver Glycogenosis Caused by a Defective Phosphorylase System: Hemolysate Analysis

PEDIATRICS ◽  
1981 ◽  
Vol 67 (1) ◽  
pp. 107-112
Author(s):  
C. Baussan ◽  
N. Moatti ◽  
M. Odievre ◽  
A. Lemonnier
Keyword(s):  
Glycogen Storage Disease ◽  
Kinase Activity ◽  
Storage Disease ◽  
Tolerance Test ◽  
Glycogen Storage ◽  
Enzyme Assays ◽  
Phosphorylase Kinase ◽  
Phosphorylase Activity ◽  
Activation Curve ◽  
Glucosidase Activity

Investigated were 24 cases of glycogenosis caused by a reduction in liver phosphorylase activity. The intravenous glucagon tolerance test could not discriminate between phosphorylase kinase deficiency [glycogen storage disease (GSD) IX] and phosphorylase deficiency (GSD VI). These two subgroups were distinguished by hemolysate enzyme assays: (1) GSD IX was characterized by a residual phosphorylase kinase activity, a low activation curve for endogenous phosphorylase b and increased amylo-1,6-glucosidase activity. (2) GSD VI was characterized by a normal or increased phosphorylase kinase activity, a slight activation of endogenous phosphorylase b and a normal amylo-1,6-glucosidase activity.

Phosphorylase and glycogen levels in skeletal muscle and liver of hibernating and nonhibernating bats

1959 ◽  
Vol 197 (5) ◽  
pp. 1059-1062 ◽  
Author(s):  
Samuel L. Leonard ◽  
William A. Wimsatt
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Liver Glycogen ◽  
Myotis Lucifugus ◽  
Phosphorylase Activity ◽  
Activity Ratios ◽  
Muscle Phosphorylase ◽  
Wet Weight ◽  
Muscle Phosphorylase Activity ◽  
Made In

Determinations of skeletal muscle and liver glycogen concentration and active a and total t phosphorylase activities were made in bats ( Myotis lucifugus) hibernating at 3°–5° and 20 hours after arousal at room temperature. After arousal, liver glycogen was decreased by half and muscle glycogen was increased over twofold. Concomitantly, muscle phosphorylase a was increased, phosphorylase t was unchanged and the ratio a/t was increased. In the liver, phosphorylase a, t and the ratios were increased upon arousal (calculated per unit of wet weight and per mg N). Epinephrine treatment was ineffective in the torpid hibernating bats, but in aroused bats, it decreased muscle and liver glycogen but increased muscle phosphorylase activity ratios only slightly. Histamine was ineffective in the aroused bats. Stimulating aroused bats to fly for short periods consistently resulted in lower muscle glycogen levels and in no change in muscle phosphorylase activity ratios. It is concluded that a) at least part of the increased muscle glycogen in the aroused bats comes from the liver, b) the changes in glycogen levels and phosphorylase activity are in some manner related and c) liver phosphorylase changes upon arousal, unlike that in muscle phosphorylase, involves an increase in total enzyme potential.

scholarly journals THE EFFECT OF SOME FACTORS ON THE HISTOCHEMICAL DEMONSTRATION OF LIVER GLYCOGEN PHOSPHORYLASE ACTIVITY

1972 ◽  
Vol 20 (5) ◽  
pp. 331-335 ◽  
Author(s):  
L.-A. LINDBERG ◽  
A. PALKAMA
Keyword(s):  
Enzyme Activity ◽  
Light Microscope ◽  
Ethylenediaminetetraacetic Acid ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Liver Glycogen ◽  
Inhibitory Effect ◽  
Histochemical Demonstration ◽  
Phosphorylase Activity ◽  
Glycogen Phosphorylase Activity

Existing methods for the histochemical demonstration of liver phosphorylase activity were investigated for possible application to a study of enzyme activity using the electron microscope as well as the light microscope. It was found that lead, in concentrations recommended in the literature, cannot be used as the precipitating agent because of its inhibitory effect on phosphorylase activity. The histochemical method based on the demonstration of enzymatically formed glycogen can be improved by adding ethylenediaminetetraacetic acid to the incubating solution. However, the addition of 3',5'-cyclic adenosine monophosphate is not as effective. It is not necessary to add glycogen to the incubating solution. In our opinion enzyme activity cannot yet be demonstrated electron microscopically by the precipitation of liberated phosphate. This is due to the inhibitory effect of high lead concentrations. Under the light microscope the method based on the demonstration of enzymatically formed glycogen is most reliable.

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