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

The isolated rat liver perfused for 12 hours at pH 7.10 with a suspension of bovine erythrocytes in Krebs-Ringer bicarbonate buffer containing 3 per cent bovine serum albumin has been used as a test system to study effects of glucagon and of dexamethasone in the presence and absence of insulin on net biosynthesis of rat serum albumin, fibrinogen, alpah1-acid glycoprotein, alpha2-(acute phase) globulin, and haptoglobin. Quantitative measurement of perfusate glucose, amino acid nitrogen, and urea affords a basis for determining net glucose and nitrogen balance in the perfusion system. Although the dose of dexamethasone (total 1.0 mug.) used was insufficient to induce synthesis of alpha2-acute phase globulin, net syntheses of albumin, fibrogen, alpha1-acid glycoprotein, and haptoglobin were increased. Glucagon given with dexamethasone depressed albumin and haptoglobin synthesis markedly, but not that of fibrinogen and alpha1-acid glycoprotein. Glucagon with dexamethasone markedly enhanced ureogenesis and glycogenolysis and elicited an exaggerated negative nitrogen balance. The unfavorable effects of glucagon on albumin and haptoglobin synthesis and on nitrogen balance were reversed by giving insulin simultaneously. It is emphasized that insulin is essential for positive nitrogen balance.
 ...
PMID:Direct effects of glucagon on protein and amino acid metabolism in the isolated perfused rat liver. Interactions with insulin and dexamethasone in net synthesis of albumin and acute-phase proteins. 6 Nov 40

Extracts of homogenates of rat, mouse, rabbit, and human submaxillary salivary glands contain a significant quantity of a material with glucagon-like immunoreactivity. Fractionation of this material on columns of Sephadex G-100 reveals a single peak immediately following a gamma globulin marker but in advance of a rat growth hormone marker, crystalline amylase, and isotopically labeled porcine insulin and glucagon. This material, which is urea stable, shows identical immunoassay dilution curves when measured with the highly specific K-30 glucagon antiserum. Study of paired glands in vitro shows that low concentrations of glucose stimulate and high concentrations of glucose suppress release of this material. Arginine promotes brisk release in vitro. Somatostatin does not influence arginine-stimulated secretion and insignificantly suppresses basal release in vitro. These findings lend support to previous speculations that the salivary glands may possess endocrine as well as exocrine functions. Salivary gland glucagon may also be the source of circulating glucagon recently reported in pancreatectomized and eviscerated rats.
 ...
PMID:Salivary gland hyperglycemic factor: an extrapancreatic source of glucagon-like material. 6 92

Two groups (each of 6 moderately ill, protein-depleted patients) were infused daily for 7 days. Mean 7 day nitrogen (N) balances with infusions of 0.83 and 1.83 g of a defined amino acid mixture (containing further nutrients but no other source of energy)/kg ideal body wt/day were -3.66 and +1.54 g/day, respectively (P less than 0.025) when adjusted for changes in body urea and estimated miscellaneous N losses. Concentrations of plasma free fatty acids, immunoreactive insulin and glucagon, and of blood glucose, pyruvate, lactate and glycerol were indistinguishable on corresponding treatment days in the 2 groups but blood ketone bodies were lower in the 1.83 g/kg group. Blood amino acid concentrations of alanine, valine, leucine, and isoleucine were similar, whereas those of phenylalanine, histidine, serine, and arginine were higher, and glutamine lower, in the 1.83 g/kg group. The data confirm that not only can body protein mass be maintained, but a net positive N retention achieved, in such patients, through provision of exogenous amino acids and concurrent mobilization of endogenous energy stores. Of note is that this fat mobilization can occur without plasma free fatty acids and/or significant blood ketone body elevations. An infusion of 2, rather than 1 g/kg/day seems suitable in the situation examined.
 ...
PMID:Intravenous protein-sparing therapy in patients with gastrointestinal disease. 11 60

It has been suggested that the hyperglucagonemia observed in diabetic animals and man may be due to an impairment of glucose uptake and metabolism by the alpha-cells resulting in a decreased production of ATP. To test this hypothesis glucose, ATP, glucagon, and insulin were measured in pancreatic islets of normal and alloxan or streptozotocin diabetic rats. Two experimental approaches were used. In the first, the pancreas was perfused in vitro for assessing insulin and glucagon release due to 10 mM amino acids with and without 5 mM glucose. These perfusions were performed in the presence and absence of insulin. After perfusion, the pancreas was frozen and processed for analysis of islet glucose, ATP, insulin, and glucagon content. The second approach was to investigate the islet sucrose, urea, and glucose spaces together with ATP, insulin, and glucagon content in vivo in normal and in insulin-treated and untreated streptozotocin diabetic rats. Perfusion of the pancreas in vitro with 5 mM glucose resulted in higher glucose content of normal islets than in alloxan and streptozotocin diabetic islets. Similarly in the in vivo studies, the intracellular glucose space of the streptozotocin diabetic islets was 30% the value found in normals. In the in vivo experiments, despite the relatively small intracellular glucose space of alpha-cell islets, the ATP content of these islets was only 15-20% lower than the ATP content of normal islets. In the in vitro experiments, perfusion with glucose resulted in ATP contents of alpha-cell islets and of normal mixed alpha-beta-cell islets which were indistinguishable. However, the ATP content of alpha-cell islets was maintained for prolonged periods in the absence of glucose in contrast to mixed islets, composed primarily of beta-cells, in which the ATP level decreased by 45% when glucose-free medium was perfused for sustained periods. Finally, insulin infused in high concentrations or administered to the diabetic animal had no effect on the glucose spaces or the ATP contents of normal or alpha-cell islets. It can be calculated that in vivo the intracellular glucose level of islets from streptozotocin treated rats is approximately 15 mM. Since in normals an extracellular glucose concentration of this magnitude inhibits stimulated glucagon release completely, it would seem unlikely that a lack of intracellular glucose is the cause of the apparent glucose "blindness" of the alpha-cells in diabetes. In fact, in perfusion studies as little as 2.5 mM free intracellular glucose was sufficient to suppress glucagon secretion from diabetic alpha-cells. The results of the ATP measurements clearly eliminate a possible energy deficit of diabetic alpha-cells as cause of the apparent glucose resistance of alpha-cells.
 ...
PMID:Glucose and ATP levels in pancreatic islet tissue of normal and diabetic rats. 13 53

A case of N-3 pyridylmethyl-N' 4 nitrophenyl urea (Vacor) rodenticide poisoning in a 52-year-old man is presented. Vacor is structurally related to alloxan and streptozotocin, agents that have been used extensively to produce diabetes mellitus in laboratory animals. Seven days after ingestion of Vacor, the patient presented in diabetic ketoacidosis complicated by postural hypotension and adynamic ileus. The patient recovered from ketoacidosis but has continued to require insulin. With infusion of arginine, glucagon rose from 185 to 650 pg./ml. and C-peptide from 0.5 to 3.4 ng./ml. Six weeks after onset of diabetes, no anti-islet-cell antibodies were detected. Muscle capillary basement membrane thickness on electron microscopy was found to be 1,918 +/- 194 A. The absence of hyperglycemia after Vacor ingestion should not lead to complacency on the part of the attending physician. The patient must be observed closely for development of ketoacidosis and treated prophylactically with nicotinamide, the suggested antidote.
 ...
PMID:Diabetes mellitus and autonomic dysfunction after vacor rodenticide ingestion. 15 23

An enzymatic method is described for isolating intact parenchymal cells from rat livers. 3--4 g cells (wet weight) could be isolated from livers of rats weighing 180--230 g. After an in vitro preperfusion of 15 minutes with a Ca-free buffer, collagenase (200 mg/1) and calcium chloride (5.2 mmol/1) were added. Perfusion was continued for another 15 minutes at 37 degrees C. Micromorphological integrity of cell membranes was demonstrated by scanning electron microscopy. With regard to rates of gluconeogenesis and protein synthesis, parenchymal cells isolated according to our method were found to be superior to liver slices and cells isolated by other methods. Ratios of ATP/ADP (5.69) and of lactate/pyruvate (8.64) as parameters of the energetic situation and the redox state resp. were found within the physiological range. Integrity of cell surface receptors was proved by their sensitivity to epinephrine, glucagon and insulin. Glucagon (0.3 mumol/1) and epinephrine (1 mumol/1) and reduced glycogen deposition in hepatocytes of fasted rats by 84.9 % and 95.9 % resp. Both hormones stimulated glycogenolysis in parenchymal cells of fed rats to a similar extent. Urea synthesis was stimulated 29.5 % by glucagon (1 mumol/1), and inhibited 28.0 % by insulin (10 nmol/1). The stimulatory effect of glucagon (1 mumol/1) was abolished by insulin (10 nmol/1).
 ...
PMID:[Isolation of intact liver parenchymal cells by a modified enzymatic method]. 16 41

The effects of ACTH on 3',5'-cyclic AMP (cAMP) levels and lipolysis were examined on isolated adipocytes incubated in either isosmolar or hyperosmolar media. The ability of ACTH to induce intracellular cAMP accumulation was greatly enhanced by incubating cells in hyperosmolar sucrose (100 to 400 mM) solutions. Hyperosmolar solutions prepared by the addition of either NaCL, glucose or mannitol enhanced the ACTH effect on cAMP to the same extent as did the hyperosmolar sucrose solution, but hyperosmolar urea solutions did not have such an effect. The effect of hyperosmolarity was shown only in cells stimulated by lipolytic hormones, and the effects were still evident in the presence of high concentrations of theophylline, indicating the effect of hyperosmolarity is to facilitate hormone action on the receptor-coupler system of the adipocyte membrane. The action of glucagon on cAMP was augmented much less than the actions of ACTH and isoproterenol. Basal as well as ACTH or exogenous cAMP stimulated lipolysis was lower in hyperosmolar sucrose solutions. Some mechanism by which hyperosmolarity interferes with the metabolic sequence beyond the accumulation of cAMP was suggested.
 ...
PMID:Effects of hyperosmolarity on the cyclic AMP concentration and lipolysis of the adipocyte stimulated by adrenocorticotropic hormone. 17 96

We have reported previously that increasing amounts of immunoreactive glucagon (IRG), measured by four specific antisera, appeared in plasma of depancreatized insulin-deficient dogs. It was therefore concluded that pancreatectomy was not accompanied by glucagon deficiency in the dog, but instead excessive amounts of extrapancreatic IRG could contribute to the diabetic syndrome. In order to locate the source of extrapancreatic glucagon, tissue extracts were assayed with anti-glucagon sera 30-K and K-44, which cross-react minimally with crude gut extracts. IRG was detected in all gastrointestinal tissues and in the salivary glands, but not in extracts of liver, kidney, brain, heart atrium, and adenohypophysis. Immunologic dilution curves of extracts from all gastrointestinal tissues were parallel to those of the pure pancreatic glucagon standard, and both antisera (30-K and K-44) measured the same concentrations. The highest concentration of gastrointestinal IRG was found in the fundus and corpus of the stomach. Presence of IRG in gastrointestinal tissues of depancreatized dogs indicates that gastrointestinal cells can not only secrete but also store large amounts of IRG. Extracts of mucosa of stomach fundus were further purified by gel filtration on Biogel P-30 columns. The immunoreactivity in the eluate was assayed by 30-K and a strongly crossreacting antibody, K-4023. One pooled fraction corresponding to marker pancreatic glucagon in its elution volume was found to contain the largest amount of IRG and the highest specific immunoreactivity (IRG/protein concentration). This fraction showed also the highest activity in a glucagon-receptor assay system. Disc gel electrophoresis in the presence of urea resolved this fraction into three immunoreactive components, one of which was identical to pancreatic glucagon in its electrophoretic mobility. It appears, therefore, that mucosa of the upper stomach in the dog contains a polypeptide similar to pancreatic glucagon. We conclude that (a) hyperglucagonemia in the dog can result from excessive secretion of IRG not only by the pancreatic alpha cells but also by cells of the gastrointestinal tract; (b) the highest IRG concentration was found in fundus and corpus of the stomach and lower concentrations throughout the gastrointestinal tract; (c) the IRG component in the stomach displayed immunologic and physical properties similar to pancreatic glucagon.
 ...
PMID:Measurement and partial characterization of immunoreactive glucagon in gastrointestinal tissues of dogs. 18 45

1. Rat hearts were perfused with 32Pi, and contractile force was increased by positive inotropic agents (agents that increase contractility). The inhibitory subunit of troponin (troponin I) was then isolated by affinity chromatography in 8M-urea, and its 32P content measured. Incorporation of phosphate into the subunit was calculated on the basis of the [gamma-32P]ATP specific radioactivity in the hearts. 2. When hearts were perfused with 30 nM-DL-isoprenaline (N-isopropylnoradrenaline), there was an increase in contractile force over 30s which was paralleled by an increase in troponin I phosphorylation. When hearts were perfused for 25s with increasing concentrations of isoprenaline from 1 NM to 0.6 muM, there was again a parallel increase in contractile force and troponin I phosphorylation. The maximum phosphorylation observed was 1.5 mol of phosphate/mol of troponin I, which was reached after 25s with 0.1 muM-isoprenaline. 3. Hearts were stimulated with a 15s pulse perfusion of 30nM-DL-isoprenaline. There was an increase in contractile force which was followed by a return to the control value within 50s. Troponin I phosphorylation increased to a plateau value which was reached within 30s, and remained constant for 60s after the isoprenaline pulse. Phosphorylase a and 3':5'-cyclic AMP concentration showed changes similar to that of the contractile force. There was no change in 3':5'-cyclic GMP concentration. 4. When hearts stimulated with a 15S pulse of isoprenaline were subsequently perfused with 0.6 muM-acetylcholine, the changes in contractile force, phosphorylase a and 3':5'-cyclic AMP were very similar to those seen with the 15s pulse of isoprenaline alone. Troponin I phosphorylation increased to a maximum 30s after the end of the isoprenaline pulse, but then rapidly decreased during the subsequent 30s. This decrease was preceded by a 60% increase in the concentration of 3':5'-cyclic GMP. 5. Hearts were perfused with 0.2 muM-glucagon for periods up to 60s. Contractile force showed little change for the first 30s, but then increased rapidly. This was paralleled by changes in 3':5'-cyclic AMP concentration. Troponin I phosphorylation increased slowly, but the increase in contractile force had reached a maximum before significant phosphorylation had occurred. 6. It is concluded that under certain conditions, e.g. immediately after beta-adrenergic stimulation, there is a good correlation between contractile force and troponin I phosphorylation. However, under other conditions, e.g. when contractile force is decreasing after removal of beta-adrenergic stimulation or in the presence of glucagon, contractile force and troponin I phosphorylation are not well correlated. These results suggest that mechanisms for modifying cardiac contractility, other than troponin I phosphorylation, must be present in rat heart.
 ...
PMID:Studies on the phosphorylation of the inhibitory subunit of troponin during modification of contraction in perfused rat heart. 18 17

The present study was designed to identify the physicochemical, immunologic, and biologic properties of the immunoreactive glucagon (IRG) moieties of canine gastric fundus and to compare them with those of the canine pancreas. Acid-alcohol extracts of the gastric fundus and pancreas of dogs were subjected to Bio-Gel P-10 chromatography, The elution profiles of extracts of both organs revealed IRG peaks in the Mr = 2,000 3,500, and 9,000 zones; in the gastric extracts, a void volume peak was also present. On the basis of Sephadex G-150 rechromatography and sucrose density gradient ultracentrifugation the latter IRG was estimated to have a Mr = 65,000. Incubation of fundic IRG65,000 in 8 M urea failed to alter its elution position. Its pI was 6.4, while fundic IRG3,500 had a pI of 6.15 and pancreatic glucagon 6.25. Fundic IRG9,000 had a pI of 4.5 and pancreatic IRG9,000 4.65. Dilution curves of these three fundic and two pancreatic IRGs were parallel to crystalline beef-pork glucagon. The glycogenolytic activity of fundic IRG3,500 and IRG65,000, measured in the isolated rat liver system, was not different from that of immunoequivalent amounts of dog pancreatic glucagon or crystalline beef-pork glucagon. Both fundic and pancreatic IRG9,000 were devoid of glycogenolytic activity and lacker adenylate cyclase stimulating activity and 125I-glucagon displacing activity when tested on partially purified rat liver membranes. Fundic IRG65,000, however, stimulated adenylate cyclase and displaced 125I-glucagon to the same degree as immunoequivalent amounts of pancreatic glucagon. Fundic IRG3,500 was more active than pancreatic glucagon in stimulating adenylate cyclase activity. This was not clearly attributable to differences in binding to liver cell membranes.
 ...
PMID:Properties of immunoreactive glucagon fractions of canine stomach and pancreas. 19 45


1 2 3 4 5 6 7 8 9 10 Next >>