Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The total arylsulphatase activity and the relative activities of lysosomal arylsulphatases A and B were measured in the liver of control rats and rats subjected to treatments that provoke hepatic autophagocytosis. The total liver arylsulphatase activities were increased in starved and starved glucagon-treated rats, but not in sham-operated and hepatectomized rats. Arylsulphatases A and B in the mitochondrial-lysosomal (M-L) fraction were separated by polyacrylamide-gel electrophoresis at pH 8.8; they were made visible by incubating the gels with p-nitrocatechol sulphate as substrate, and measured by quantitative densitometry. In untreated controls, arylsulphatases A and B comprised 41.4 +/- 0.5% and 58.6 +/- 0.5% of the total arylsulphatase activity respectively; the arylsulphatase A/arylsulphatase B activity ratio was 0.71. All experimental treatments produced a significant decrease in the percentage of lysosomal arylsulphatase present as the A form and an increase in that present as the B form, and the activity ratio of arylsulphatase A/arylsulphatase B declined. The magnitude of these changes increased in the following direction: starvation for 24h=sham hepatectomy less than glucagon + starvation less than subtotal hepatectomy. These results indicate that the arylsulphatase A/arylsulphatase B activity ratio in liver lysosomes of normal rats is maintained within rather narrow limits, and this ratio declines during enhanced autophagocytosis. These findings, together with observations that suggest that arylsulphatase B may be a partially degraded form of arylsulphatase A, are consistent with the view that the A form is more rapidly converted into the B form during autophagy, owing to the digestive activity of the other lysosomal hydrolases present in autophagic vacuoles.
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PMID:Autophagy-related changes of arylsulphatases A and B in rat liver lysosomes. 0 37

The activity of the putative ketogenic beta-oxoacyl-CoA thiolase from mitochondria of rat liver increases with starvation, during neonatal life, and after the injection of glucagon. These changes are associated with alteration in ketonaemia. The changes in activities of this species of thiolase are not associated with significant alterations in the apparent affinity (Km) for the ketogenic substrate, acetyl-CoA. These results support a role for thiolase in the regulation of ketogenesis.
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PMID:Effects of starvation and development on mitochondrial acetoacetyl-coenzyme A thiolase of rat liver. 1 45

Factors contributing to modifications in the capability for enzyme adaptation as an expression of aging are reviewed. Specific examples of altered enzyme adaptations during aging include the responses of hepatic glucokinase activity to glucose and hepatic tyrosine aminotransferase activity to starvation in Sprague-Dawley rats. These impaired enzyme adaptations apparently are not the consequence of alterations in hepatic function during aging. Instead, they reflect disturbances in extrahepatic hormonal regulatory mechanisms. Specific examples include modifications in the control of circulating levels of insulin glucagon, corticosteroids, and thyroid hormones. Age-dependent changes in the regulation of circulating levels of insulin probably originate within the impaired ability of pancreatic islets of Langerhans to secrete the hormone in response to glucose. The rationale for exploiting this experimental approach as a means to understand biological aging is discussed.
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PMID:Loss of adaptive mechanisms during aging. 3 73

Everted intestinal rings from partially starved rats accumulate the nonmetabolized amino acid 1-amino-cyclopentane-5-carboxylic acid (ACPC) at an enhanced rate. Plasma glucagon concentrations were found to be markedly elevated in these partially starved rats as well as in rats with experimentally induced diabetes, a condition previously shown to be associated with augmented intestinal uptake of amino acid. Treatment of partially starved rats with repeated injections of glucagon-binding antiserum prevented increased ACPC uptake of intestinal rings. Chronically elevated plasma glucagon levels may participate in the mechanism of the functional changes in the intestine in partial starvation.
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PMID:Treatment with glucagon-binding antibodies alters the intestinal response to starvation in the rat. 12 36

When washed spleen slices from fed rats are incubated with 3 mm-[U-14C]glucose, the rate of glucose utilization (46.2 mumol/h per g dry wt.) is sufficient to account, theoretically, for 80% of the O2 consumption. Measurement of net lactate production, however, and the fate of the radioactive carbon, indicates that the contribution of glucose to the respiratory fuel of the tissue is only 25-30% whereas 60-70% of the glucose utilized is converted into lactate. At saturating glucose concentrations (above 5 mm) its contribution to the respiratory fuel of the slice is increased to a maximum value of 34-39%. Only 2% of the glucose utilized is metabolized via the oxidative steps of the pentose phosphate pathway. Starvation for 72 h marginally increases both the rate of glucose utilization (by 21%) and its net contribution to the respiratory fuel (by 29%). Insulin, glucagon, adrenaline and adenosine 3':5'-cyclic monophosphate have no significant effect on either the rate of glucose utilization or on the pattern of radioactive isotope distribution. The uptake of glucose is increased by only 20%, whereas the production of lactate doubles when slices are incubated under anaerobic conditions. In assessing the suitability of spleen slices for metabolic studies, the only serious major perturbation, compared with the freeze-clamped organ, is an elevated mitochondrial [NAD+]/[NADH] ratio (connected with increased endogenous NH3 production) that is partially restored to normal values on incubation with glucose. Equal proportions of erythrocytes and leucocytes are found in the washed spleen slice. Metabolic contributions of the constituent cell populations in the washed slice are calculated and it is concluded that lymphocytes account for the major part of the glycolytic metabolism (80-90%), whereas the contribution of erythrocytes is insignificant.
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PMID:Regulation of carbohydrate metabolism in lymphoid tissue. Quantitative aspects of [U-14C]glucose oxidation by rat spleen slices. 17 88

The present investigations of rates of oxidation of [U-14C] or [1-14C]leucine by homogenates of gastrocnemius muscle of fed and starved rats have indicated that 14CO2 production is mainly the result of alpha-decarboxylation of leucine in this tissue. This incomplete oxidation was not the result of imparied tricarboxylic acid cycle since the oxidation of palmitate proceeded to completion within the experimental conditions. In the subsequent studies, the effect of altered nutrition and metabolic factors on alpha-decarboxylation of leucine by gastrocnemius muscle homogenates was investigated. Starvation increased the rate of alpha-decarboxylation of leucine. Glucose or palmitate (C16) added in physiological concentrations to the incubation medium were without effect on decarboxylation of leucine, but this reaction was stimulated by addition of 1 mM hexanoate (C6) or octanoate (C8) to the incubation medium. However, when fatty acid chain length was elongated to C10 (decanoate), the stimulatory effect was not only abolished, but this fatty acid significantly inhibited the rate of leucine decarboxylation. Addition of insulin, epinephrine, glucagon and cyclic AMP within a wide range of concentrations to the incubation medium did not significantly affect the rate of decarboxylation of leucine. These studies indicate a complex interrelationship between the metabolism of leucine and that of fatty acids.
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PMID:Assessment of effect of starvation, glucose, fatty acids and hormones on alpha-decarboxylation of leucine in skeletal muscle of rat. 18 44

The concentration of insulin and glucagon in peripheral blood and the concentration of cAMP in liver was followed in rats throughout a 48 hour starvation period and up to 6 hours afer refeeding glucose or casein. By so changing the insulin/glucagon molar ratio from minimum to maximum values, simultaneous inverse changes in the concentration of hepatic cAMP could be induced. The study, thus, suggests that during a starvation-refeeding cycle the level of cAMP in the liver is regulated predominantly by the insulin/glucagon ratio in the blood. Possible criticisms of this conclusion are discussed.
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PMID:Concentration of cyclic AMP in rat liver as a function of the insulin/glucagon ratio in blood under standardized physiological conditions. 18 53

The physiologic significance of glucocorticoids and insulin in the regulation of hepatic gluconeogenesis was investigated during a 48-hr starvation period by studying the factors presumed to control the rate of glucose synthesis in the final gluconeogenetic pathway. Rats were used, in which glucorticoids were removed by adrenalectomy before starvation, and in which serum insulin was kept constant before and after food withdrawal by pre-feeding with a proteinfree diet. It was found that adrenalectomized rats at constantly low serum insulin levels responded to starvation as rapidly, and to the same degree, as intact control subjects (1) by a significant increase in plasma glucagon and, consequently, in hepatic cAMP concentration; (2) by a coordinate elevation of the activities of hepatic pyruvate carboxylase, P-enolpyruvate carboxykinase, and fructose-1,6-diphosphatase; (3) by systematic alterations in the concentration of effectors of gluconeogenetic key enzymes; (4) by a shifting of the cytoplasmic NAD system towards the reduced state; (5) by a decrease in the intrahepatic concentration of glycogenic precursor substrates. These results suggest that the hepatic gluconeogenic response to starvation with respect to the regulatory factors 1-5 occurs independently from changes in the concentration of plasma glucocorticoids and insulin. The crossing over of the gluconeogenetic intermediates between pyruvate and P-enolpyruvate (PEP), which was observed in intact but not in adrenalectomized rats, supports the assumption that during starvation, glucocorticoids enhance the rate of glucose production by the liver predominantly by permitting hepatic cAMP to stimulate the yet undefined mechanism, which has been demonstrated in the isolated perfused rat liver to control the substrate flow between pyruvate and PEP.
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PMID:Physiologic significance of glucocorticoids and insulin in the regulation of hepatic gluconeogenesis during starvation in rats. 18 90

1. The development of glycerolkinase before and after birth was investigated in liver and kidney of rat and hamster. In rat liver, enzyme activity increased very slowly before birth and rapidly thereafter, reaching adult values at the 6th day of postnatal life. In hamster liver, glycerolkinase was considerably elevated already in utero, increased dramatically within the 1st day of postnatal life and reached adult values at the end of the 1st week. The development of hepatic glycerolkinase was compared with that of hepatic phosphoenolpyruvate carboxykinase of rat and hamster up to the 20th day of postnatal life. The different time-courses of the levels of these two enzymes before and after birth as well as the known kinetics of serum insulin, glucagon and corticosterone during that time suggested that none of these hormones is involved in the perinatal development of hepatic glycerolkinase activity. In contrast to liver, kidney glycerolkinase activity in both, rat and hamster, showed a delayed increase during the first week of postnatal life followed by a more pronounced elevation to adult values within the following 2 weeks. 2. When liver and kidney glycerolkinase activity was investigated during starvation (+/- refeeding), in alloxan diabetes(+/- insulin) and after adrenalectomy (+/- cortisol) no significant change in enzyme activity per g tissue could be detected either in liver or in kidney. However, total hepatic glycerolkinase activity was diminished during starvation as a consequence of decreasing liver weight. 3. Incorporation of U-[14C]-glycerol into CO2, lipids and glucose + glycogen by rat liver and kidney cortex slices was studied under the above gluconeogenetic conditions. Despite unchanged glycerolkinase activity in both organs, gluconeogenesis from glycerol was enhanced during starvation and in chronic alloxan diabetes, and could be reversed by refeeding and insulin replacement, respectively. 4. Feeding 20% of linolic acid to normal, alloxan-diabetic or adrenalectomized rats resulted in a significant increase in glycerolkinase activity in liver but not in kidney. 5. From the present findings it is suggested that the first step of gluconeogenesis from glycerol in liver and kidney is not influenced by glucagon, insulin and glucocorticoids, which are generally believed to regulate the rate of gluconeogenesis from non-glycerol precursors, but probably by the change in blood glycerol concentration.
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PMID:Glycerolkinase--a regulatory enzyme of gluconeogenesis? 18 91

The glycogen pellet of dog liver extracts contains a phosphorylase phosphatase which has characteristics different from those of the phosphatases extracted from the cytosol. The phosphatase associated with glycogen is characterized by a M, of 51,000, a half maximal inhibition at 0.3 mM ATP (Hill coefficient : 2) and a Ki for Mg2+ of 1 mM. Treatment with urea or mercaptoethanol of the phosphatase associated with glycogen does not influence the activity, the Mr or the half maximal inhibition by ATP, but a decrease of the Hill coefficient for ATP is observed. A similar treatment of the phosphatases extracted from the high speed supernatant results in a decrease of the Mr of the spontaneously active form from 215,000 to 43,000, without an effect on the Ki for ATP (7 micronM), but accompanied by an increase in activity. The ATP-Mg dependent form of the phosphatase from the high speed supernatant (Mr : 138,000 ; Ka for ATP in the presence of 0.1 mM Mg2+ : 0.3 micronM), is denatured by urea or mercaptoethanol. The phosphatase associated with particulate glycogen cannot be found in the supernatant, nor the phosphorylase phosphatases present in the supernatant in the glycogen pellet. When all the glycogen is mobilized (starvation, glucagon) the phosphatase specifically associated with glycogen cannot be found as such in the cytosol. No activation of synthase beta can be detected neither with the phosphatases extracted from the cytosol nor with the enzyme released from the glycogen pellet.
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PMID:Multiple molecular forms of phosphorylase phosphatase associated with particulate glycogen and extracted from the cytosol of dog liver. 19 25


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