GLYCOGEN SYNTHETASE ACTIVITY IN THE RAT UTERUS

SUMMARY Glycogen synthetase, phosphorylase and glycogen were determined biochemically in the smooth muscle of the rat uterus following a single s.c. injection (10 μg.) of oestradiol dipropionate. The ovariectomized animals were killed 6, 12, 24, 48, 72 and 96 hr. after the hormone treatment. From 12 to 96 hr. glycogen synthetase activity was significantly greater than in the untreated control rats. Phosphorylase activity was significantly less than in the controls at 12 hr. and greater from 48 to 96 hr. After the initial drop, control phosphorylase values were obtained between 24 and 48 hr. From 12 to 96 hr. the glycogen concentration was greater than in the control animals. The results show that oestrogen increased glycogen synthetase activity in the smooth muscle of the uterus soon after the hormone treatment, and with the increase in enzymic activity the glycogen concentration was also increased. They indicate that, during the early phase of glycogen synthesis, oestrogen stimulates glycogenesis by increasing glycogen synthetase activity and suppresses glycogenolysis by inhibiting phosphorylase activity. The glycogen concentration at later stages did not alter significantly, and this may have been due to the build-up and breakdown of the carbohydrate by the action of glycogen synthetase and phosphorylase, respectively.

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Glycogen Metabolism in Glycogen-rich Erythrocytes

Blood ◽

10.1182/blood.v44.2.275.275 ◽

1974 ◽

Vol 44 (2) ◽

pp. 275-284 ◽

Cited By ~ 2

Author(s):

Shimon W. Moses ◽

Nova Bashan ◽

Alisa Gutman ◽

Per Arne Ockerman

Keyword(s):

Red Blood Cells ◽

Blood Cells ◽

Glycogen Synthesis ◽

Glycogen Metabolism ◽

Linear Increase ◽

Synthetase Activity ◽

Glycogen Synthetase ◽

Cell Age ◽

Degradative Enzymes ◽

High Concentrations

Abstract High concentrations of red blood cell glycogen were visualized by electron microscopy and demonstrated biochemically in amylo-1,6-glucosidase- and phosphorylase-deficient red blood cells. Glycogen concentration decreased as a function of cell age. Similar incorporation rates of 14C-U-glucose into glycogen were observed in amylo-1,6-glucosidase-deficient and normal erythrocytes, characterized by an initial rise, followed by a plateau formation reflecting a steady state between glycogen synthesis and breakdown. A different pattern of kinetics was observed in phosphorylase-deficient cells, which in view of the lack of the degradative enzyme showed a continuous linear increase in radioactive glycogen formation leveling off only after exhaustion of substrate. Evidence that in amylo-1,6-glucosidase-deficient red blood cells the main metabolic activity affects the outer branches of the glycogen molecule was obtained directly by β-amylolytic degradation of the radioactive glycogen molecule and indirectly by a chase experiment substituting radioactive with nonlabeled glucose. Normal glycogen synthetase activity was found in all cases of amylo-1,6-glucosidase examined except in one family in which an unexpected low affinity of the enzyme to glycogen was found. The observation that both amylo-1,6-glucosidase- and phosphorylase-deficient red blood cells retain the capacity to incorporate glucose into glycogen indicates that glycogen synthesis in erythrocytes proceeds along the UDPG glycogen synthetase pathway and is not a result of a reverse activity of any of the degradative enzymes.

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Glycogen synthetase activity of the rat uterus following progesterone stimulation

Steroids ◽

10.1016/s0039-128x(68)80109-6 ◽

1968 ◽

Vol 12 (4) ◽

pp. 457-464 ◽

Cited By ~ 4

Author(s):

Walter J. Bo ◽

Martha J. Ashburn

Keyword(s):

Synthetase Activity ◽

Rat Uterus ◽

Glycogen Synthetase

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Mise en évidence de glycogène et d'une activité de la glycogène synthétase dans l'ébauche hépatique aux stades précoces du développement embryonnaire chez le poulet

Development ◽

10.1242/dev.32.3.637 ◽

1974 ◽

Vol 32 (3) ◽

pp. 637-650

Author(s):

Elisabeth Houssaint ◽

Nicole M. Le Douarin

Keyword(s):

Chick Embryo ◽

Developmental Stages ◽

Glycogen Synthesis ◽

Electron Microscopic Level ◽

Synthetase Activity ◽

Electron Microscopic ◽

Glycogen Synthetase ◽

Somite Stage ◽

Early Developmental Stages ◽

Early Developmental

Detection of glycogen and glycogen synthetase activity in the hepatic primordium of chick embryo at early developmental stages Glycogen has been detected cytochemically in the chick hepatic primordium at early developmental stages. The cytochemical methods used are PAS according to Hotchkiss & MacManus after fixation by Gendre's fluid at −20 °C and rapid dehydration at 4 °C and Thiery's technique for polysaccharide detection at the electron microscopic level. Previous authors reported that glycogen appears in the hepatocytes during the sixth or seventh day of incubation in the chick embryo. In fact, the more sensitive methods used here show that this substance is present in the determined presumptive hepatic endoderm as early as the 20-somite stage, some hours before the formation of the primary hepatic bud. Glycogen is present in an approximately constant amount in the differentiating hepatic endoderm as β particles (according to Drochmans' nomenclature) from the 20-somite stage to the sixth day of incubation. Then the hepatocyte glycogen content increases rapidly as had previously been shown by biochemical methods and α rosettes appear in the cell. A glycogen synthetase activity has been detected at the end of the fourth day of incubation (96 h). This activity increases sharply from the sixth day of incubation to reach a maximal value at .12 days and then decreases until hatching. The possible regulatory mechanisms of glycogen synthesis in differentiating liver cells of avian embryos are discussed.

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Hormonal regulation of glycogen metabolism in neonatal rat liver

Biochemical Journal ◽

10.1042/bj1340985 ◽

1973 ◽

Vol 134 (4) ◽

pp. 985-993 ◽

Cited By ~ 29

Author(s):

Alan L. Schwartz ◽

Theodore W. Rall

Keyword(s):

Cyclic Amp ◽

Rat Liver ◽

Hormonal Regulation ◽

Glycogen Metabolism ◽

Hormonal Control ◽

Neonatal Rat ◽

Synthetase Activity ◽

Dibutyryl Cyclic Amp ◽

Glycogen Concentration ◽

Glycogen Synthetase

1. The development of active and inactive phosphorylase was determined in rat liver during the perinatal period. No inactive form could be found in tissues from animals less than 19 days gestation or older than the fifth postnatal day. 2. The regulation of phosphorylase in organ cultures of foetal rat liver was examined. None of the agents examined [glucagon, insulin or dibutyryl cyclic AMP (6-N,2′-O-dibutyryladenosine 3′:5′-cyclic monophosphate)] changed the amount of phosphorylase activity. 3. Glycogen concentration in these explants were nevertheless decreased more than twofold by 4h of incubation with glucagon or dibutyryl cyclic AMP. Incubation with insulin for 4h increased the glycogen content twofold. 4. Glycogen synthetase activity was examined in these explants. I-form activity (without glucose 6-phosphate) was found to decrease by a factor of two after 4h of incubation with dibutyryl cyclic AMP, whereas I+D activity (with glucose 6-phosphate) remained nearly constant. Incubation for 4h with insulin increased I-form activity threefold, with only a slight increase in I+D activity. 5. When explants were incubated with insulin followed by addition of dibutyryl cyclic AMP, the effects of insulin on glycogen concentration and glycogen synthetase activity were reversed. 6. These results indicate that the regulation of glycogen synthesis may be the major factor in the hormonal control of glycogen metabolism in neonatal rat liver.

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Effects of Insulin and Testosterone on Glycogen Synthesis and Glycogen Synthetase Activity in Rat Levator Ani Muscle

Acta Physiologica Scandinavica ◽

10.1111/j.1748-1716.1973.tb05450.x ◽

1973 ◽

Vol 88 (2) ◽

pp. 234-247 ◽

Cited By ~ 8

Author(s):

Sten Adolfsson

Keyword(s):

Glycogen Synthesis ◽

Levator Ani ◽

Levator Ani Muscle ◽

Synthetase Activity ◽

Glycogen Synthetase

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GLYCOGEN PHOSPHORYLASE AND GLYCOGEN SYNTHETASE ACTIVITY IN RED AND WHITE SKELETAL MUSCLE OF THE GUINEA PIG

Canadian Journal of Biochemistry ◽

10.1139/o65-054 ◽

1965 ◽

Vol 43 (4) ◽

pp. 463-468 ◽

Cited By ~ 19

Author(s):

Sydney St. George Stubbs ◽

M. C. Blanchaer

Keyword(s):

Skeletal Muscle ◽

Guinea Pig ◽

Glycogen Phosphorylase ◽

White Muscle ◽

Synthetase Activity ◽

Fiber Types ◽

Phosphorylase Activity ◽

Glycogen Synthetase ◽

Red Muscle ◽

Wet Weight

Glycogen phosphorylase (α-1,4-glucan:orthophosphate glucosyltransferase) and glycogen synthetase (UDPG:α-1,4-glucan α-4-glucosyltransferase) have been examined in red and white skeletal muscle of the guinea pig. Histochemically phosphorylase was found to be more active in white than in red muscle fibers but no difference in glycogen synthetase could be detected between the fiber types. However, quantitative determinations showed that total glycogen synthetase activity (I + D) was higher in red than in white muscle (1.46 ± 0.14 S.E.M. vs. 0.71 ± 0.09 μmoles/minute per g wet weight at 37°). The converse relationship held for total phosphorylase activity (a + b), which was greater in white than in red muscle (19.24 ± 2.93 vs. 10.43 ± 2.34 μmoles/minute per g wet weight at 30°). The phosphorylase a level of 3.63 ± 0.96 in red muscle at rest was similar to that of 5.44 ± 1.19 in resting white muscle. Stimulation produced a significant conversion of phosphorylase b to a only in white muscle. After 30 seconds stimulation with 1-volt impulses of 20 milliseconds duration at a rate of 20 pulses per second, the phosphorylase a activities of red and white muscle were respectively 3.72 ± 1.88 and 16.66 ± 1.79. After stimulation the glycogen synthetase values in white and red muscle were 1.02 ± 0.07 and 1.72 ± 0.11 respectively.

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