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)

Hepatocytes and Kupffer cells were separated from rat liver after prelabeling the Kupffer cells with colloidal iron and perfusion of the liver with digestive enzymes. The activity of several enzymes from Kupffer cells and hepatocytes was compared to validate this method of cell separation. The ratios of hepatocyte to Kupffer cell specific activities of glucose-6-phosphatase, 5'-nucleotidase, adenylate cyclase, and acid phosphatase were 20, 0.39, 0.18, and 0.078, respectively. Adenylate cyclases from hepatocytes and Kupffer cells were stimulated by fluoride ion, GTP, and catecholamines. Hepatocyte adenylate cyclase was also stimulated by glucagon, secretin, vasoactive intestinal polypeptide, and by prostaglandin E1, whereas, the Kupffer cell enzyme was completely insensitive to these hormones. The stimulation of hepatocyte adenylate cyclase by combinations of glucagon plus secretin, or glucagon plus vasoactive intestinal polypeptide, were equivalent to the sum of the individual stimulations. This suggests that the hepatocyte has specific receptors for glucagon and for vasoactive intestinal polypeptide and secretin. Prostaglandin E1 stimulation of hepatocyte adenylate cyclase was not additive to the stimulation caused by polypeptide hormones or catecholamines, nor did prostaglandin E1 decrease stimulation caused by these hormones. Although prostaglandin-sensitive adenylate cyclase was recovered with hepatocytes, 40 to 50% of the total liver prostaglandin-sensitive activity was recovered in a fraction of cell debris mixed with small cells which did not phagocytize colloidal iron.
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PMID:Stimulation of adenylate cyclase from isolated hepatocytes and Kupffer cells. 17 Dec 69

Sub-total pancreatectomy in utero was performed in 18-day-old rat foetuses. Pancreatectomized, sham-operated and control foetuses were collected 3 days later and body weight, glucose and insulin levels in blood, and glycogen content and glucose-6-phosphatase (G-6-Pase) activity of the liver were determined. Pancreatectomized foetuses showed only very small pancreatic remnants (less than or equal to 1 mg) and accordingly their insulin levels were much lower (four to five times) than those of sham-operated or control foetuses; their blood glucose levels were slightly increased and liver glycogen content and G-6-Pase activity were slightly reduced; their body weights were also reduced. These results are discussed in relation to other relevant data in the literature. They afford direct experimental evidence of the endogenous origin of insulin in the foetal blood. It is suggested that during the last days of intra-uterine life insulin merely completes the action of the glucocorticoids on glycogen storage in rat foetal liver and probably contributes to foetal body growth. Its relative ineffectiveness on the foetal blood glucose level is not explained. As pancreatectomized foetuses develop sub-normal liver G-6-Pase activity, glucagon is probably not responsible for the increase in this activity occurring during normal development before birth.
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PMID:Effects of sub-total gastro-intestinal pancreatectomy of the rat foetus. 17 17

During hepatic regeneration a drop in the liver glycogen content along with a lower blood glucose level have been observed. These data are difficult to correlate with the rise of blood glucagon and the drop of insulin shown at the same times after partial hepatectomy. Therefore, liver glucose-6-phosphatase activity has been studied at 1.5, 4, 15 and 24 h, since that enzyme is involved in the release of glucose from the cell. 4 and 15 h after partial hepatectomy a remarkable decrease in glucose-6-phosphatase activity is observed. These results are discussed in view of the higher metabolic demand of regenerating liver.
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PMID:[Activity of glucose-6-phosphatase during liver regeneration]. 23 47

Other investigators have shown that fructose infusion in normal man and rats acutely depletes hepatic ATP and P(i) and increases the rate of uric acid formation by the degradation of preformed nucleotides. We postulated that a similar mechanism of ATP depletion might be present in patients with glucose-6-phosphatase deficiency (GSD-I) as a result of ATP consumption during glycogenolysis and resulting excess glycolysis. The postulate was tested by measurement of: (a) hepatic content of ATP, glycogen, phosphorylated sugars, and phosphorylase activities before and after increasing glycolysis by glucagon infusion and (b) plasma urate levels and urate excretion before and after therapy designed to maintain blood glucose levels above 70 mg/dl and thus prevent excess glycogenolysis and glycolysis. Glucagon infusion in seven patients with GSD-I caused a decrease in hepatic ATP from 2.25 +/- 0.09 to 0.73 +/- 0.06 mumol/g liver (P <0.01), within 5 min, persisting in one patient to 20 min (1.3 mumol/g). Three patients with GSD other than GSD-I (controls), and 10 normal rats, showed no change in ATP levels after glucagon infusion. Glucagon caused an increase in hepatic phosphorylase activity from 163 +/- 21 to 311 +/- 17 mumol/min per g protein (P <0.01), and a decrease in glycogen content from 8.96 +/- 0.51 to 6.68 +/- 0.38% weight (P <0.01). Hepatic content of phosphorylated hexoses measured in two patients, showed the following mean increases in response to glucagon; glucose-6-phosphate (from 0.25 to 0.98 mumol/g liver), fructose-6-phosphate (from 0.17 to 0.45 mumol/g liver), and fructose-1,6-diphosphate (from 0.09 to 1.28 mumol/g) within 5 min. These changes, except for glucose-6-phosphate, returned toward preinfusion levels within 20 min. Treatment consisted of continuous intragastric feedings of a high glucose dietary mixture. Such treatment increased blood glucose from a mean level of 62 (range 28-96) to 86 (range 71-143) mg/dl (P <0.02), decreased plasma glucagon from a mean of 190 (range 171-208) to 56 (range 30-70) pg/ml (P <0.01), but caused no significant change in insulin levels. Urate output measured in three patients showed an initial increase, coinciding with a decrease in plasma lactate and triglyceride levels, then decreased to normal within 3 days after treatment. Normalization of urate excretion was associated with normalization of serum uric acid. We suggest that the maintenance of blood glucose levels above 70 mg/dl is effective in reducing serum urate levels and that transient and recurrent depletion of hepatic ATP due to glycogenolysis is contributory in the genesis of hyperuricemia in untreated patients with GSD-I.
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PMID:ATP depletion, a possible role in the pathogenesis of hyperuricemia in glycogen storage disease type I. 27 29

To determine the fetal response to altered maternal fuel supply, the effects of prolonged maternal fasting, begun 24-96 h before term, were examined and compared with values from normally fed term animals. Fetal weight decreased only after 48 h of maternal fasting. Prolonged maternal fasting was associated with low blood glucose, high blood ketone bodies, and decreased gluconeogenic substrate in the fetus. Plasma insulin was decreased, whereas plasma glucagon was increased in the fetus of fasted mothers. Infusion of [2-3H]glucose into the mother to constant specific activity gave a ratio of maternal to fetal glucose activity of 1.0 in fed and 1.56 in fasted mothers. Fetal liver from fasted mothers showed both increase in activity of key gluconeogenic enzymes (glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) and increased conversion in vitro of lactate, alanine, serine, and glycerol in glucose by liver slices. It is inferred that maternal fasting induces fetal substrate alterations and hormonal changes appropriate to premature appearance of hepatic gluconeogenesis. The priority for endogenous fuel provision in this state leads to impaired fetal growth.
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PMID:Fetal metabolic response to maternal fasting in the rat. 87 Nov 55

Glycogen storage diseases are usually identified in childhood. We present the clinical, biochemical and histological features of 10 patients first diagnosed in adult life. Five had glycogen storage disease type 1a, one type 1c, two type IX, and in two patients there were previously unreported abnormalities of hepatic glucose-6-phosphatase system activity. Of the latter, one patient had an inhibitor of liver glucose-6-phosphatase (pseudo-1b glycogen storage disease) the other having abnormal glucose-6-phosphatase activity and microsomal pyrophosphate transport. A glucagon test is suggested as a useful screening procedure. Glycogen storage disease should be considered in adults with symptoms suggesting hypoglycaemia.
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PMID:Glycogen storage disease diagnosed in adults. 132 55

French experience of 242 cases of liver glycogenoses is reported. Screening tests based on serum biochemical data and glucagon tolerance tests are briefly reviewed. The diagnosis of types I glycogen storage disease (GSD) was ascertained in 73 patients' liver biopsies by measurement of glycogen content and by studying the glucose-6-phosphatase system. Liver biopsies were also required at the beginning for the diagnosis of other hepatic GSDs; later on, the possibilities of diagnosis using peripheral blood cells were investigated. Eighty-four cases of type III GSD were confirmed by measurement of debranching enzyme activity and glycogen content using either liver biopsies (78 cases) and/or erythrocytes (37 cases); enzyme determination was also performed in leukocytes and/or fibroblasts for 18 patients. Twenty-four cases of type VI GSD underwent liver biopsies, and the diagnosis could be confirmed using mononuclear or polymorphonuclear cells for 11 of these patients. Sixty-one patients were identified as type IX GSD; phosphorylase kinase deficiency was demonstrated in erythrocytes for all patients, and a liver biopsy was analyzed for 26 of these cases. From this experience, the possibilities of diagnosis of liver GSD using peripheral blood cells are emphasized.
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PMID:Biochemical diagnosis of hepatic glycogen storage diseases: 20 years French experience. 164 31

Severe reactive hypoglycaemia was confirmed in a non-diabetic male patient by a counter-regulatory hormone (GH, cortisol and catecholamine) response to profound hypoglycaemia induced by an intravenous glucose load. There was also evidence of disordered pancreatic islet cell paracrine regulation with hyperinsulinaemia and absent glucagon response to hypoglycaemia. A defect in the patient's hepatic glucose-6-phosphatase enzyme system was documented. Because of severe symptoms, dietary control was insufficient, but the patient responded clinically and biochemically to 18 months of oral diazoxide therapy. He also showed good biochemical response to a single dose (100 micrograms IM) of the somatostatin analogue octreotide.
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PMID:Reactive hypoglycaemia in association with disordered islet function and abnormal hepatic glucose-6-phosphatase activity: response to diazoxide. 183 18

Colenol, a diterpenoid isolated from the roots of Coleus forskohlii stimulates the release of insulin and glucagon from the islets both in vitro and in vivo. Colenol-stimulated release of glucagon from islets in vitro is much more pronounced as compared to that of insulin. Glucose concentration of 5.6 mM in the medium is required for the colenol stimulation of insulin release. Feeding of coleonol to alloxan diabetic rats cause 36.5% increase in blood glucose level as compared to alloxan diabetic control. Oral feeding of coleonol for 7 days to normal rats causes increase in blood glucose, serum insulin, glucagon and free fatty acid levels with corresponding increase in glucose-6-phosphatase activity and depletion of liver glycogen. Predominant stimulation of A-cells by coleonol is suggested for the above effects.
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PMID:Insulin and glucagon releasing activity of coleonol (forskolin) and its effect on blood glucose level in normal and alloxan diabetic rats. 165 May 16

The contribution of hormone-stimulated glycogenolysis to hepatic glucose production was studied in hepatocytes from streptozotocin diabetic rats. To this end, the activation of glycogen phosphorylase by glucagon, vasopressin, and the alpha 1-adrenergic agonist phenylephrine was compared in hepatocytes from normal and diabetic rats and related to glycogen content, glucose production, and microsomal glucose-6-phosphatase activity. Streptozotocin-induced diabetes reduced the glycogen content and the amount of total (a + b) phosphorylase in hepatocytes proportionally to the severity of the disease. In cells from severely diabetic rats (group 1), the responsiveness of activation of phosphorylase to the hormones was reduced by about half, consistent with a 45% reduction in total phosphorylase. In addition, the sensitivity of phosphorylase activation to all hormones investigated was decreased by about 1 order of magnitude or more in cells of this group. In hepatocytes from rats with milder diabetes (group 2), maximal phosphorylase activation reached an intermediate value between that of the control group and of group 1. In response to all hormones investigated, group 2 diabetic rat hepatocytes produced less glucose than control rat liver cells, while in group 1 there was no increase in glucose production at all, presumably because glycogen concentration was too low. However, in group 2 diabetic rat hepatocytes, glucagon-stimulated glucose production, unlike phosphorylase activation, did not show decrease sensitivity, presumably because glucose-6-phosphatase activity is increased by diabetes. Our results thus indicate that hormone-stimulated liver glycogenolysis is unlikely to contribute to enhanced glucose production in insulin-deficient diabetes, despite increased glucose-6-phosphatase activity.
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PMID:Hormone-stimulated glucose production from glycogen in hepatocytes from streptozotocin diabetic rats. 165 43


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