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)

Residual beta cell function was studied in 18 juvenile-onset diabetics by measuring serum C-peptide immunoreactivity (CPR) fasting, and after IV injection of glucagon (1 mg). This was compared with the exocrine pancreatic response to an IV infusion of secretin and cholecystokinin-pancreozymin. Outputs of pancreatic bicarbonate, amylase and trypsin were measured. Exocrine secretory pancreatic function was decreased in 14 patients. Fasting and maximal CPR showed that 9 patients had residual insulin secretion. For these 'CPR-secretors' there was a strong correlation between CPR and output of bicarbonate (r = 0.87, p less than 0.005) and amylase (r = 0.7, p less than 0.05), but not with trypsin. These results suggest the existence of an endocrine-exocrine relationship in the pancreas.
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PMID:The effect of residual insulin secretion on exocrine pancreatic function in juvenile-onset diabetes mellitus. 34 40

The uptake by rat yolk sacs of native invertase and invertase which was deglycosylated by treatment with endo-beta-N-acetylglucosaminidase was compared. The initial rate of uptake of the deglycosylated enzyme was severalfold greater and its accumulation leveled off much earlier than that of the native enzyme. Uptake rates of the deglycosylated and native forms of the enzyme were proportional to their concentration in the medium in the range employed and were inhibited about 85% by 10(-6) M glucagon in both cases. After preloading of yolk sacs with native invertase, the tissue level of activity remained relatively constant over a subsequent 6-h time period, while with the deglycosylated form, activity declined substantially. Since this difference appears not to be attributable to differences in thermal stability, it is suggested that the deglycosylated form of the protein is more susceptible to intracellular proteolytic digestion. In vitro studies on the digestion of these two forms of invertase by trypsin are consistent with this suggestion.
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PMID:Effect of deglycosylation of yeast invertase on its uptake and digestion in rat yolk sacs. 37 2

Exocrine pancreatic function was investigated by means of the Lundh test model in dogs with chronic duodenal and gastric fistulas. The test was standardized and the effect of glucagon on exocrine pancreatic secretion was evaluated. The mean tryptic activity detected in 18 tests in 6 dogs was 32.25 +/- 5.25 muEqH+/minute/ml, which is considerably higher than that observed in man. The administration of glucagon was followed by a significant decrease (30.8%) in the volume of the duodenal contents and a more pronounced depression of the enzyme concentrations (trypsin 59%, chymotrypsin 53.3%). It is concluded that the Lundh test affords a valuable experimental model for the investigation of exocrine pancreatic function in dogs.
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PMID:Influence of glucagon on exocrine pancreatic function as determined by the Lundh test in dogs. 59 92

Pancreatitis was induced in 11 miniature pigs by infusing a bile salt-trypsin solution into the pancreatic duct. Seven animals served as sham-operated controls. Serum ionized calcium, total calcium, albumin, total protein, inorganic phosphorus, urea nitrogen, magnesium, insulin, glucagon, and hematocrit were determined every six to 12 h over a period of one week in both test and control animals. We observed significant decreases in ionized and total calcium, modest decreases in albumin, and significant increases in the inorganic phosphorus, urea nitrogen, and hematocrit in the pancreatitic pigs. The latter two findings were consistent with early acute hypovolemia. Glucagon and insulin appeared to play no role in the hypocalcemia. Glucagon concentrations increased to the same degree in both test and control animals, probably as a result of the stress of being handled and operated on. The highest concentrations of inorganic phosphorus and the lowest concentrations of both ionized and total calcium were seen 18 h after the induction of pancreatitis in the test animals. These findings suggest that parathyrin (parathormone) was not being secreted in adequate amounts, or that the target organs were unresponsive to parathyrin.
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PMID:Biochemical changes in a porcine model of acute pancreatitis. 65 76

Enteropeptidase, trypsin, and chymotrypsin activity in basal and secretin-stimulated duodenal juice of 20 normal adult volunteers and 15 patients with gastrotestinal disease were determined. All enzyme concentrations showed skew distributions, but fluctuations in the secretin-stimulated juices were less pronouced than in the basal secretions. Secretin administration had no influence on the release of enteropeptidase from human duodenal mucosa, but resulted in a very small increase in secretion of pancreatic enzymes. Six out of seven patients with chronic alcoholic pancreatitis or cancer of the pancreas exhibited highly significant elevations of enteropeptidase in their basal as well as secretin-stimulated duodenal juice. It is suggested that raised luminal enteropeptidase activity may be the result of pancreatic insufficiency or elevated blood glucagon concentrations.
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PMID:Enteropeptidase levels in duodenal juice of normal subjects and patients with gastrointestinal disease. 66 28

The role of cytosol components in the loss of rat liver adenylate cyclase activity which occurs during the preparation of particulate fractions from crude homogenates was studied. Epinephrine (5 micron)-, glucagon (10 micron)-, and fluoride (5 mM)- stimulated activities of twice-washed particulates were 31%, 58% and 67% of the homogenate activities, respectively. Addition of cytosol (100,000 X g supernatant devoid of adenylate cyclase activity) restored these activities to 82%, 88% and 80%. Cytosol also increased particulate basal activity from 60% of homogenate activity to 98%. The cytosol components capable of increasing adenylate cyclase activity were heat labile, nondialyzable, stable to freezing at -20 degrees, resistant to change of pH between 2 and 12, and unaffected by EGTA and NAD. Pretreatment with pepsin destroyed the effects of cytosol on both epinephrine- and glucagon-sensitive activities, whereas trypsin destroyed the effect of cytosol only on epinephrine-sensitive activity. The cytosol effect on adenylate cyclase was specific, since several purified proteins and ubiquitin, did not stimulate enzyme activity. Only part of the cytosol effect could be attributed to its GTP content. GTP at the concentration present in cytosol stimulated epinephrine-sensitive activity but significantly less than did cytosol, while GTP had no effect on glucagon-sensitive activity. Dialyzed cytosol retained its effectiveness even after removal of most (97%) of its GTP to a concentration where GTP had only a minimal effect on epinephrine-sensitive activity. Cytosol, unlike GTP, stimulated rather than inhibited activation by fluoride. Cytosol thus appears to contain at least two different protein components, which increase the activity of the two hormone-sensitive adenylate cyclases and presumably account in part for losses of adenylate cyclase activities seen during the preparation of particulates from homogenates.
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PMID:Activation of epinephrine and glucagon-sensitive adenylate cyclases of rat liver by cytosol protein factors. Role in loss of enzyme activities during preparation of particulate fractions, quantitation and partial characterization. 72 79

The cytosolic fraction from rat liver enhanced the basal and glucagon-sensitive adenylate cyclase (EC 4.6.1.1) of hepatic plasma membranes and revealed its (R)-(-)-epinephrine sensitivity. Such phenomena were usually obtained by the addition of low concentrations of GTP to the medium employed for the cyclase assay. Comparative studies of the behavior of the cytosolic factor and GTP in response to various treatments were performed. We present evidence that the stimulatory activity of the soluble factor was reduced after treatment by alkaline phosphatase, by the nucleotide phosphohydrolases present in the plasma membranes, and by trypsin. These results strongly suggest that the soluble activator is a nucleotide-protein complex and further demonstrate that GTP may be of physiological significance in the regulation of the adenylate cyclase system.
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PMID:Activation of epinephrine-sensitive adenylate cyclase in rat liver by cytosolic protein-nucleotide complex. 85 3

Plasma immunoreactive glucagon (IRG) concentrations were measured in 36 patients with chronic renal failure (CRF) and 32 normal subjects. In addition, the components of circulating IRG were analyzed by gel filtration in the fasting state and after physiological stimuli. Fasting IRG was elevated (P less than 0.001) in CRF patients (534 +/- 32 pg/ml) compared with the levels found in healthy subjects (113 +/- 9 pg/ml). Oral glucose suppressed plasma IRG in CRF patients from a basal level of 568 +/- 52 to a nadir of 354 +/- 57 pg/ml (120 min). This degree of suppression (38%) was comparable to that found in normal subjects (basal = 154 +/- 20 to 100 +/- 23 pg/ml) at 120 min (35%). Intravenous infusion of arginine (250 mg/kg) resulted in a 71% rise in IRG in CRF patients and a 166% increase in normal subjects. Gel filtration of fasting plasma from CRF patients showed three major peaks. The earliest (A) was found in the void volume (mol wt greater than 40,000) and constituted 16.5 +/- 4.7% of the elution profile. The middle peak (B) eluted just beyond the proinsulin marker (approximately 9,000 mol wt) and constituted the largest proportion of the elution profile (56.5 +/- 3.4%). The third peak (C) coincided with the standard glucagon and [125I]glucagon markers (3,485 mol wt) and comprised 27.0 +/- 4% of the IRG profile. In contrast, only peaks A and C were found in fasting plasma of normal subjects (53.6 +/- 10.4% in A and 46.4 +/- 10.4 in C). After oral glucose, glucagon immunoreactivity in the 3,500 mol wt peak (C) was markedly suppressed, while the B peak in patients with CRF declined to a lesser extent. The A peak in both groups was unchanged. After an arginine infusion only the C peak increased in both groups of subjects. Gel filtration of plasma in 3 M acetic acid gave similar profiles to those obtained in glycine albumin buffer. Exposure of serum to trypsin indicated that the B and C peaks were digestible, while the A peak was resistant to the action of the enzyme. In one sample, peak C increased after a 2-h exposure of serum to trypsin. We conclude that circulating IRG in normal subjects and patients with CRF is heterogenous. The hyperglucagonemia of renal failure is largely due to an increase in IRG material of approximately 9,000 mol wt, consistent with proglucagon, although the 3,500 mol wt component is also considerably elevated (threefold). The significance of circulating IRG levels should be interpreted with caution until the relative biological activity of the three components is established.
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PMID:Heterogeneity of plasma glucagon. Circulating components in normal subjects and patients with chronic renal failure. 95 99

Analysis of the plasma from a totally pancreatectomized patient, with antiserum 30 K, has demonstrated basal glucagon immunoreactivity (GIR) levels in the normal range (80-110 pg/ml). Neither i. v. arginine nor oral glucose affected these GIR values, thus indicating the absence of functioning pancreatic or gastrointestinal A-cells. Furthermore, filtration of whole plasma on Bio Gel P-30 showed no GIR in the 3500 MW elution volume. GIR was found to be distributed in two peaks. One peak eluted in the protein region, similarly to "big plasma glucagon" (BPG), and the second peak appeared after the glucagon-I125 marker. The protein-sized moiety was not absorbable by charcoal, and on Sephadex G-100 it eluted within the globulin region. When subjected to trypsin treatment, it yielded smaller GIR fractions. According to these criteria, it can be assumed that this component is identical to BPG. Therefore, an extrapancreatic source for BPG is suggested. On the other hand, the presence of fasting hyperglycaemia in this patient indicates that insulin deficiency by itself suffices to raise blood sugar to diabetic levels.
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PMID:Plasma glucagon immunoreactivity in a totally pancreatectomized patient. 100 50

Evidence is presented that proglucagon from anglefish islets is a single chain polypeptide with 78 amino acid residues and that the glucagon portion of it is liberated after tryptic cleavage. The most striking characteristic in the conversion of the anglerfish proglucagon to glucagon is that the cleaved peptide bonds display enormous sensitivity toward trypsin. Thus, conversion of the prohormone to glucagon occurs very rapidly within 3-10 min with a 1:500-1:1000 molar ratio of enzyme to substrate. Further, trypic cleavage of the anglerfish glucagon requires higher concentrations of trypsin (molar ratio 1:25 enzyme to substrate) and longer incubation time. The behavior of proglucagon and glucagon toward trypsin shows striking similarities with the tryptic conversion of anglerfish proinsulin to insulin.
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PMID:Isolation and partial characterization of anglefish proglucagon. 109 38


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