Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of long-term starvation on glucagon-mediated hepatic glycogenolysis was investigated in the rat in vivo. Following glucagon (50 microgram/kg i.v.) fed rats showed rapid phosphorylase activation but no change in synthase-I activities. In contrast, rats fasted 72 hr (long-term fasting) showed rapid synthase inactivation but no significant phosphorylase activation. Rats fasted 24 hr (short-term fasting) demonstrated coordinated inactivation of synthase and activation of phosphorylase. Hepatic cyclic AMP responses were greater in fasted rats. Hepatic glycogen concentrations in rats fasted 72 hr were approximately 30% of fed levels. After glucagon, comparable decrements in hepatic glycogen and increments in plasma glucose concentrations were seen in fed and 72-hr groups. The diminished responsiveness of the hepatic phosphorylase system in rats fasted 72 hr was not attributable to altered cyclic AMP-dependent protein kinase or phosphorylase kinase activities. However, the diminished responsiveness could be ascribed to diminished total phosphorylase with nearly complete activation in the basal state. In fed and fasted rats, synthase decrements after glucagon correlated closely with basal levels of synthase-I. Thus, it is proposed that the enzymatic mechanism of glucagon-mediated hepatic glycogenolysis differs in fed and fasted rats. It is also proposed that partial hepatic glycogen reaccumulation during long-term fasting could be physiologically important for glucose homeostasis.
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PMID:Altered mechanism of glucagon-mediated hepatic glycogenolysis during long-term starvation in the rat. 21 68

We have studied the changes in concentration of glycogen, glucose and the bisphosphorylated sugars, glucose 1,6-P2 and fructose 2,6-P2, in several rat brain regions during 72 h of starvation. The animals were killed by focused microwave irradiation. The activities of glycogen metabolizing enzymes in the different areas were measured. A large decrease in glycogen and glucose concentration was observed in all areas. The concentrations of bisphosphorylated sugars changed, suggesting that an increase in glycolysis could take place at the beginning of starvation, with blood glucose as a major energy source. Differences in metabolite concentration before starvation disappeared after 72 h. The activities of glycogen synthase, glycogen phosphorylase and glycogen phosphorylase kinase were similar in all areas, and they did not change during starvation.
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PMID:Effect of starvation on glycogen and glucose metabolism in different areas of the rat brain. 144 41

The effects of food deprivation on body weight, liver weight, hepatic glycogen content, glycogenolytic enzymes and blood metabolites were compared in young and old phosphorylase b kinase-deficient (gsd/gsd) rats. Although the concentration of glycogen in liver from 9-week-old female gsd/gsd rats (730 mumol of glucose equivalents/g wet wt.) was increased by 7-8% during starvation, total hepatic glycogen was decreased by 12% after 24 h without food. In 12-month-old male gsd/gsd rats the concentration of liver glycogen (585 mumol of glucose equiv./g wet wt.) was decreased by 16% and total hepatic glycogen by nearly 40% after food deprivation for 24 h. Phosphorylase b kinase and phosphorylase a were present at approx. 10% of the control activities in 9-week-old gsd/gsd rats, but both enzyme activities were increased more than 3-fold in 12-month-old affected rodents. It is concluded that the age-related ability to mobilize hepatic glycogen appears to result from the augmentation of phosphorylase b kinase during maturation of the gsd/gsd rat.
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PMID:Age-related augmentation of phosphorylase b kinase in hepatic tissue from the glycogen-storage-disease (gsd/gsd) rat. 309 76

Intraperitoneal injection of 3-mercaptopicolinate into 24 h-food-deprived 27-week-old female control (GSD/GSD) rats lowered the concentration of circulating glucose by 66%, but glycerol and lactate concentrations were increased up to 3- and 4-fold respectively. In phosphorylase b kinase-deficient (gsd/gsd) rats the corresponding changes for blood glucose, lactate and glycerol were half those observed in the controls. Although the concentration of liver glycogen (approx. 12%, w/w) in the gsd/gsd rats was not altered during food deprivation, total hepatic glycogen was decreased by 17%. It is suggested that the gradual breakdown of the extensive hepatic glycogen stores during starvation assists in the maintenance of normoglycaemia in the gsd/gsd rat.
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PMID:Effects in vivo of food deprivation and 3-mercaptopicolinate in the glycogen-storage-disease (gsd/gsd) rat. 386 52

Rats from an inbred strain (NZR/Mh) were found to have high concentrations of glycogen in their livers, even after 24 h of starvation. Despite this, blood glucose concentrations were well maintained on starvation for up to 72 h. The primary defect is a deficiency of liver phosphorylase kinase, causing a lack of active glycogen phosphorylase, although total phosphorylase is normal. The intravenous injection of glucagon caused a rapid activation of cyclic AMP-dependent protein kinase in the liver, but no increase in either phosphorylase kinase or phosphorylase a activity. Although total glycogen synthase activity in the livers of affected rats was higher than normal, glycogen synthase in the active form was very low, presumably as a result of the high liver glycogen content. The condition is transmitted as autosomal recessive and, apart from hepatomegaly, the affected rats appear healthy.
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PMID:Glycogen-storage disease in rats, a genetically determined deficiency of liver phosphorylase kinase. 693 96

The livers of gsd/gsd rats homozygous for the glycogen storage disease phosphorylase b kinase deficiency were observed by 13C NMR using a surface coil. Clear signals were detected from glycogen. The concentration of glycogen as determined by NMR was approximately 3-times that found in normal strains agreeing well with chemical determinations. Starvation did not significantly reduce the glycogen content of the livers with glycogen storage disease whereas it reduced the signal below detectability in normal rats. Difference spectra of starved normal rats from fed gsd/gsd rats gave spectra similar in appearance to that of purified glycogen. Glycogen both in vivo and in vitro is fully visible using 13C NMR.
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PMID:Detection of glycogen in a glycogen storage disease by 13C nuclear magnetic resonance. 696 87

Disturbances of carbohydrate metabolism during acute uraemia are characterized by the degradation of liver and muscle glycogen with a simultaneous activation of hepatic gluconeogenesis. After binephrectomy, the substitution of essential amino acids and keto analogues stimulate liver, but not skeletal muscle glycogen synthesis. Serine proves to be an optimal substrate for liver gluconeogenesis and muscle glycogen generation under acute uraemic conditions. Propranolol does not influence glycogenolysis of skeletal muscle in acutely uraemic rats. During starvation, acute uraemia leads to an increase of total carbohydrate content as well as of glycogen and glucose concentrations in heart muscle Alterations in carbohydrate contents are not observed in the kidney after ureter ligation. Enhanced glycogenolysis of skeletal muscle and liver during acute uraemia may be due to activation of phosphorylase kinase caused by the increased serum concentrations of various hormones (glucagon, catecholamines, parathormone) as well as free proteolytic activity, an increase of intracellular Ca2+-concentration and finally by alterations in the structure of contractile proteins.
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PMID:Carbohydrate metabolism and uraemia-mechanisms for glycogenolysis and gluconeogenesis. 745 93

The enzymatic characterization of sarcoplasmic reticulum membrane fragments from rabbit skeletal muscle presented in this paper shows that glycogen phosphorylase, as well as other enzymes (e.g., creatine kinase, myokinase, phosphorylase kinase, glycosidase, AMP-deaminase, phosphoglucomutase) are associated with these membrane preparations. Amongst these enzymes, the highest activity associated with sarcoplasmic reticulum membranes is that of glycogen phosphorylase, which is mostly (at least 95%) in its b form (dephosphorylated form), since its activity in sarcoplasmic reticulum membranes is largely dependent upon AMP. A protocol is presented to quantify the amount of phosphorylase bound to sarcoplasmic reticulum membranes from fluorimetric measurements of the content of its coenzyme, pyridoxal 5'-phosphate. The content of phosphorylase ranged from 0.03 to 0.37 mg phosphorylase per mg of membrane protein, in sarcoplasmic reticulum membrane preparations made following several of the protocols most commonly used and also depending upon the length of the starvation period of the animal before killing. We also show that dilution of sarcoplasmic reticulum membranes to 0.1-0.2 mg protein per ml in a buffer containing 50 mM Tes-KOH (pH 7.4), 0.1 M KCl and 0.25 M sucrose removes at least 95% of glycogen phosphorylase from these membrane fragments, as well as other enzymes like myokinase and glycosidase. On these grounds, we suggest to introduce a final dilution step as indicated above in protocols of sarcoplasmic reticulum membrane preparations.
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PMID:Quantification and removal of glycogen phosphorylase and other enzymes associated with sarcoplasmic reticulum membrane preparations. 807 39

Upon fractionation of a post mitochondrial supernatant from rat liver, phosphorylase kinase activity was largely recovered in the cytosol and the smooth endoplasmic reticulum (SER) fraction. The presence of phosphorylase kinase in SER vesicles was not due to an interaction of the enzyme with glycogen particles, since previous elimination of SER glycogen either by 48 h animal starvation or by treatment of the membrane fraction with alpha-amylase did not significantly alter phosphorylase kinase activity content. Washing of the initial pellet of SER fraction (crude SER) by dilution and recentrifugation, released in the supernatant an amount of phosphorylase kinase activity, which is dependent on: i) the degree of dilution, ii) the number of washes, iii) the ionic strength of the washing solution and iii) the presence or absence of Ca2+. Crude SER-associated phosphorylase kinase was marginally affected by increased concentrations of antibody against rabbit skeletal muscle holoenzyme which nevertheless drastically inhibited cytosolic enzyme activity, while it showed a higher resistance to partial proteolysis and a different Western blotting profile with anti-phosphorylase kinase when compared with the soluble kinase. A small but significant fraction of SER phosphorylase kinase was strongly associated with the microsomal fraction being partly extractable only in presence of detergents. This membrane-bound enzyme form exhibited an alkaline pH optimum, in contrast to the neutral pH optima of both soluble and weakly associated phosphorylase kinase.
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PMID:The association of phosphorylase kinase with membranes of rat liver smooth endoplasmic reticulum. 871 29