Liver Glycogen Phosphorylase Activity Research Articles

2-Amino-2-deoxy- d-glucose and d- manno-heptulose as diabetogenic agents in the rat gluconeogenesis and glycogenolysis

1. 1. Rats made hyperglycemic with 2-amino-2-deoxy- d-glucose (GA) or d- manno-heptulose (MH) incorporated into blood glucose more labelled carbon, of [U- 14C] l-alanine, than did the saline injected controls. 2. 2. The specific radioactivities of the blood-glucose of the hyperglycemic rats were found to be lower than that of the controls. 3. 3. Liver glycogen-phosphorylase activity at the height of the hyperglycemia of the GA-injected rats was significantly higher, and that of the MH-treated rats higher, with slight significance, than that of the controls. 4. 4. Adrenalectomized and adrenal demedullated rats given GA showed no change in blood glucose level. The same rats given MH reacted with a marked hyperglycemia though lower than that of the intact rats.

Hyperglycemic effect of neurotensin, a hypothalamic peptide.

A hypotensive, gut-contracting peptide neurotensin (NT), recently isolated from bovine hypothalami, has been found to produce hyperglycemia within minutes after iv injection into anesthetized rats. The dose-response relationship (deltaglucose, 15 min after injection) was linear over the range 30-200 pmol/100 g BW. NT did not alter the disappearance rate of [14C]glucose from plasma during the development of the hyperglycemia. However, the peptide caused a fall in liver glycogen (52 +/- 6.5 to 41 +/- 3.3 mg/g) and a 7-fold increase in the activity of the 5'-AMP independent form of liver glycogen phosphorylase. Activation of liver glycogen phosphorylase did not occur in vitro under conditions found suitable for demonstrating the effectiveness of glucagon, suggesting the possible involvement of an intermediary substanc(s) in vivo. Acute adrenalectomy did not prevent the response. Hypophysectomized rats (4 days post-operative) were less sensitive to NT, perhaps as a consequence of their diminished liver glycogen levels (normal, 52 +/- 6.5 mg/g; hypophysectomized, 23 +/- 1.8 mg/g); however, the presence of the pituitary was not essential for this response. NT was also effective in rats with hereditary diabetes insipidus (Brattleboro strain). At the time intervals sampled, radioimmunoassayable plasma levels of growth hormone, glucagon, and insulin were not significantly changed after injection of NT into normal rats. Pretreatment of rats with reserpine (7 mg/kg), morphine sulfate (10 mg/kg), propranolol (5mg/kg), or phenoxybenzamine (10 mg/kg) did not prevent the response. These findings characterize the action of NT on liver glycogen metabolism and blood glucose levels, but a physiological role for NT in this regard remains to be demonstrated.

The activation of liver glycogen phosphorylase by angiotensin II

The activation of liver glycogen phosphorylase by angiotensin II

Evidence for the coordinate control of activity of liver glycogen synthase and phosphorylase by a single protein phosphatase.

Homogeneous rabbit liver phosphorylase phosphatase (Brandt, H., Capulong, Z. L., and Lee, E. Y. C. (1975) J. Biol. Chem. 250, 8038-8044) also dephosphorylates glycogen synthase b. During purification, phosphorylase phosphatase and glycogen synthase phosphatase co-purified with a constant ratio of activities. The two activities co-migrated on disc gel electrophoresis. Both substrates competed with each other for the phosphatase, and both phosphatase activities were inhibited by lysine ethyl ester. It is concluded that liver phosphorylase phosphatase and glycogen synthase phosphatase have a common identity and that coordinate regulation of the phosphatase-catalyzed activation of glycogen synthase and inactivation of phosphorylase occurs in vivo. This provides a parallel and opposing mechanism to that mediated by adenosine 3':5'-monophosphate-dependent protein kinase, which coordinately inactivates glycogen synthase and, via phosphorylase kinase, activates phosphorylase. Maximal glycogen synthase phosphatase activity was observed near neutrality. Mg2+ and glucose-6-P activated the glycogen synthase phosphatase reaction and this activation was pH-dependent. The Km for glycogen synthase b was 0.12 muM.

The activation of liver glycogen phosphorylase by vasopressin

The activation of liver glycogen phosphorylase by vasopressin

Acute hormonal regulation of cyclic AMP content and glycogen phosphorylase activity in fetal liver in organ culture.

Acute hormonal regulation of fetal rat liver cyclic AMP content and glycogen phosphorylase activity was examined in an organ culture system using explants from term fetuses. Phosphorylase was rapidly activated by epinephrine and glucagon; the respective minimally effective concentrations were 2 X 10−7M and 10−8M. The characteristics of the adrenergic response were denned. Following the addition of a high concentration (10−5M) of epinephrine: Phosphorylase activity increased to a maximum at one minute (the earliest time point examined) and remained unchanged for at least 30 min; cyclic AMP levels were also maximally elevated by one minute but then declined over the next 30 min. The beta antagonist propranolol blocked both effects of epinephrine; the alpha antagonist phentolamine was without effect. The predominantly beta agonist isoproterenol was much more effective in elevating cyclic AMP levels and in activating phosphorylase than the predominantly alpha agonist phenylephrine. We conclude: i. fetal rat l...

Histochemical demonstration of rat liver glycogen phosphorylase activity with iron (Fe++).

A new histochemical method for light microscopic demonstration of liver glycogen phosphorylase activity has been introduced in this study.

Lead and some other metals in the histochemical demonstration of rat liver glycogen phosphorylase activity.

Lead in a concentration of 0.25 mM was tried as a histochemical trapping agent for inorganic phosphate, liberated in the reversible reaction catalyzed by the liver glycogen phosphorylase.

Observations on the histochemically demonstrable liver glycogen phosphorylase activity and native glycogen under different nutritional conditions.

In this study a histochemical demonstration of glycogen phosphorylase activity and native glycogen in the livers from normally fed, overfed and starved rats was performed.

The effect of some factors on the histochemical demonstration of liver 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.

Diurnal variations in the response to in vivo and in vitro activation of mouse liver glycogen phosphorylase(EC2.4.1.1).

The results of in vivo and in vitro activation of mouse liver glycogen phosphorylase at two different times of the day are reported. Phosphorylase activity measured at 4 p.m. cannot be further increased over the basal level (40 umol Pi. min^-1, g^-1 fresh liver) either in vivo (epinephrine) or in vitro (ATP-Mg incubation). On the contrary, at midnight the basal level (18 umol Pi. min^-1, g^-1 fresh liver) can be increased by 50% by epinephrine in vivo, or brought to 30 umol Pi. min^-1.g^-1 fresh liver by incubation with ATP-Mg of homogenates from either control or epinephrineinjected mice. These results suggest that conversion from the inactive to the active form can account for approximately half of the daily variations in phosphorylase activity. The remaining variation might be due to other factors, e.g. de novo synthesis and degradation.

Changes in catecholamine and angiotensin levels in the cat and dog during hemorrhage.

ARTICLESChanges in catecholamine and angiotensin levels in the cat and dog during hemorrhageRC Hall, and RL HodgeRC Hall, and RL HodgePublished Online:01 Nov 1971https://doi.org/10.1152/ajplegacy.1971.221.5.1305MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByAcute hemorrhagic shock decreases airway resistance in anesthetized ratSam Bayat, Gergely Albu, Skander Layachi, Flore Portier, Marc Fathi, Ferenc Peták, and Walid Habre1 August 2011 | Journal of Applied Physiology, Vol. 111, No. 2Renal function following cardiac arrest and resuscitation in the canineResuscitation, Vol. 32, No. 3Conjunctival oxygen tension monitoring during a controlled phlebotomyThe American Journal of Emergency Medicine, Vol. 6, No. 1Pharmacotherapy of circulatory shockDisease-a-Month, Vol. 33, No. 6Regional distribution of blood flow at the onset of right ventricular diastolic collapse during cardiac tamponadeAmerican Heart Journal, Vol. 113, No. 5ACTIVE AND INACTIVE RENIN IN CRITICALLY ILL PATIENTSClinical and Experimental Pharmacology and Physiology, Vol. 12, No. 6Deterioration of metabolic coronary regulation in hemorrhagic shockResearch in Experimental Medicine, Vol. 185, No. 6Autonomic mechanisms regulating myocardial contractility in conscious animalsPharmacology & Therapeutics, Vol. 29, No. 2The importance of nervous and humoral factors in the control of vascular resistance, blood flow distribution and net fluid absorption in the cat small intestine during hemorrhageActa Physiologica Scandinavica, Vol. 121, No. 4Blood flow distribution, villous tissue osmolality and fluid and electrolyte transport in the cat small intestine during regional hypotensionActa Physiologica Scandinavica, Vol. 121, No. 3Cardiac dynamics during hemorrhage. Relative unimportance of adrenergic inotropic responses.Circulation Research, Vol. 50, No. 5Intestinal blood flowGastroenterology, Vol. 78, No. 4Effects of splanchnic nerve stimulation on cardiac preload, afterload, and output in cats.Circulation Research, Vol. 46, No. 2Beta-adrenergic dilator interaction with the constrictor response in resistance vessels of skeletal muscle during hemorrhageActa Physiologica Scandinavica, Vol. 108, No. 1Role of the renin-angiotensin system in blood pressure regulation. The cardiovascular effects of converting enzyme inhibition in normotensive subjects.Circulation Research, Vol. 45, No. 6Fluid transfer from skeletal muscle to blood during hemorrhage Importance of beta adrenergic vascular mechanismsActa Physiologica Scandinavica, Vol. 102, No. 4Effect of angiotensin-converting enzyme inhibitor (SQ 20881) on the plasma concentration of angiotensin I, angiotensin II, and arginine vasopressin in the dog during hemorrhagic shock.Circulation Research, Vol. 41, No. 3On the role of calcium as second messenger in liver for the hormonally induced activation of glycogen phosphorylaseBiochimica et Biophysica Acta (BBA) - General Subjects, Vol. 496, No. 2HUMORAL KIDNEY MEDIATION OF ADRENAL CATECHOLAMINE RESPONSE TO HEMORRHAGEThe activation of liver glycogen phosphorylase by angiotensin II19 October 2001 | FEBS Letters, Vol. 68, No. 2THE SYMPATHO-ADRENAL SYSTEM AND HEMORRHAGIC SHOCKEffects of Right Atrial Stretch on Plasma Renin Activity27 September 2008 | Archives Internationales de Physiologie et de Biochimie, Vol. 84, No. 2Blood platelet response to plasma from patients with ischemic heart diseaseThe American Journal of Cardiology, Vol. 35, No. 2Role of the Symphato-Adrenal System in Hemorrhagic HyperglycemiaActa Physiologica Scandinavica, Vol. 93, No. 1 More from this issue > Volume 221Issue 5November 1971Pages 1305-1309 Copyright & PermissionsCopyright © 1971 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1971.221.5.1305PubMed4330892History Published online 1 November 1971 Published in print 1 November 1971 Metrics

Circadian rhythm in mouse liver phosphorylase activity

Abstract Studies of the liver glycogen phosphorylase activity in mice at different times of the day have made it possible to describe circadian variations in the activity of this enzyme. These variations are closely related with the circadian variations in the glycogen content, since the highest value of the enzyme activity is reached at the time (16.00 hr) when the glycogen is maximally degradated and vice‐versa. The lowest value of phosphorylase activity was found between 24.00 hr and 4.00 hr. The difference between the peak and the trough was highly significant: p < 0.001. The estimation of the enzyme activity was performed on liver homogenates by the method described by Sutherland. The mechanisms which may be involved in the control of this rhythm are discussed. It is suggested that this rhythm may be the result of synthesis and degradation rather than activation and inactivation of the enzyme.

Control of rat liver glycogen synthetase and phosphorylase activities by glucose

In the perfused rat liver, hyperglycemia causes a rapid inactivation of phosphorylase and a conversion of glycogen synthetase from a glucose-6- P dependent form to a glucose-6- P independent form. This effect is similar in the presence or in the absence of added insulin, but is absent following adrenalectomy and fasting when glycogen synthetase phosphatase activity is not detectable. Under conditions where phosphatase activity is low, glucose increases its activity. The effect of glucose occurs in the absence of detectable alterations in tissue concentration of adenosine 3′,5′-monophosphate, the primary intracellular regulator mediating hormonal control of the activity of these enzymes. Circulating glucose levels also directly modify the effects of glucagon on the activities of these enzymes supporting the possibility that glucose levels may be important in moderating the control of liver glycogen metabolism in vivo .

Adrenal corticosteroid involvement in the control of liver glycogen phosphorylase activity

Adrenalectomy results in a marked decrease in the hyperglycemic effects of administered epinephrine and cyclic AMP. The absence of an effect with cyclic AMP suggests that the metabolic lesion resides beyond adenyl cyclase, possibly at the level of the liver phosphorylase reaction. Lack of adrenal corticosteroids results in no change in the levels of active liver glycogen phosphorylase. However, the levels of inactive enzyme are greatly diminished. Epinephrine or cyclic AMP administration does not result in activation of available inactive enzyme. Hydrocortisone replacement therapy results in restoration of inactive liver phosphorylase levels and return of the hyperglycemic effects of epinephrine and cyclic AMP. It is proposed that adrenal corticosteroids have a role in maintaining physiological phosphorylase levels and in the conversion of inactive to active phosphorylase, possibly at the level of the phosphorylase kinase kinase reaction.

Influence of glucagon and 3', 5'-AMP on insulin responsiveness of the perfused rat liver.

Influence of glucagon and 3', 5'-AMP on insulin responsiveness of the perfused rat liver.

Glucose regulation of hepatic gluconeogenesis.

Glucose regulation of hepatic gluconeogenesis.

Ursachen der St�rungen im Kohlenhydratstoffwechsel unter dem Einflu� sulfonamidierter Diuretica

Treatment with hydrochlorothiazide or furosemide does not impair the pancreatic function to increase insulin secretion in response to an elevation of blood glucose concentration. This has been shown in rats after single intravenous injection of 200 mg/kg as well as after oral application of 200 mg/kg and day of these diuretics over a period of 4 weeks. In contrast, 200 mg/kg diazoxide given intravenously causes a complete block of the glucose-inducible insulin secretion. Cellular glucose uptake measured in the presence or absence of insulin has been found unaltered after administration of the diuretics or diazoxide. Application of hydrochlorothiazide to alloxan diabetic rats results in a rise in blood glucose concentration which has not been observed in animals with unimpaired endocrine pancreatic function. The increase in blood glucose concentration induced by the diuretic benzothiadiazine has been found related to an increase in glycogenolysis caused by an inhibition of 3′,5′-AMP phosphodiesterase in liver and skeletal muscle. The decreased breakdown in 3′,5′-AMP as a result of the inhibition of the phosphodiesterase increases the hyperglycemic effect of epinephrine. Furosemide has been shown to decrease 3′,5′-AMP phosphodiesterase in liver but not in skeletal muscle of rats treated with 200 mg/kg of the diuretic. This is in accordance to an activation of liver glycogen-phosphorylase. The intensity of this enzymic activation, even in alloxan diabetic rats, does not suffice to result in a detectable rise in blood glucose. This may be explained by a compensatory uptake of glucose in skeletal muscle as application of furosemide does not lead to an accelerated glycogenolysis in this tissue reducing hexokinase activity by an increase in glucose-6-phosphate concentration. In these experiments the kidneys of the animals had been removed to avoid interference with changes in blood glucose concentration caused by an increase in catecholamine release in consequence of the diuretic effect leading to a reduction in extracellular fluid space. There is also no influence of furosemide on the hyperglycemic effect of epinephrine under the experimental conditions described.

Norethandrolone-induced changes in hepatic phosphorylase activity

Fresh liver homogenates from male mice previously treated with steroids were assayed for Phosphorylase activity and glycogen content. One hour following the injection of norethandrolone (2.0 mg./Kg.), significant decreases in liver glycogen and liver Phosphorylase activity were noted. Lower doses of norethandrolone (0.5 and 1.0 mg./Kg.) produced only moderate reductions in enzymatic activity. Norethynodrel (2.0 mg./Kg.) was also observed to reduce liver glycogen and liver Phosphorylase activity. Ethisterone and testosterone (2.0 mg./Kg.) caused slight alterations in enzymatic activity, but liver glycogen remained essentially unchanged. Cortisone administration (2.0 mg./Kg.) resulted in diminished enzymatic activity, but enhanced liver glycogen.