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 objectives of the present work were to study the role (and possible sources) of gastrin and glucagon, as measured by radioimmunoassay techniques, in the acute response to massive bowel resection in dogs. Four acute experimental models were designed for this purpose. Circulating portal and arterial hormone concentrations were estimated under basal conditions and after administration of an intraduodenal fat stimulus. Stimulated portal gastrin levels were significantly higher in animals with bowel resections than in intact animals (p less than 0.05 to p less than 0.01) but the depletion of N-terminal glucagon-like (GLI) reactivity or total GLI was only transiently significant (p less than 0.05). Pancreatectomy, with or without resection, resulted in depletion of circulating N-terminal and C-terminal GLI, although not to zero values, suggesting extra-pancreatic sources of the GLI. Portal-arterial differences were noted for GLI but not for gastrin.
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PMID:Gastrin and glucagon responses to extensive distal small bowel resection: an experimental study in dogs. 738 70

Plasma glucagon and growth hormone concentrations were measured fasting and after oral glucose in 19 patients with portal vein block with extensive portal-systemic shunting but minimal liver cell damage, 11 cirrhotic patients and 12 matched control subjects. Portal vein block patients and controls had similar fasting glucose and glucagon levels (glucose 3.8 +/- 0.1 mmol/l VS control 3.4 +/- 0.1 mmol/l (mean +/- SEM); glucagon 57.5 +/- 9.1 pg/ml VS control 51.3 +/- 7.8 pg/ml). Cirrhotic patients were hyperglycaemic (cirrhosis 4.3 +/- 0.2 mmol/l VS control 3.4 +/- 0.1 mmol/l, p < 0.01) with significantly elevated glucagon levels (167.3 +/- 61.1 pg/ml VS control 51.3 +/- 7.8 pg/ml, p < 0.05), which suppressed towards control values after oral glucose. There was no correlation between fasting plasma glucagon levels and the degree of portal-systemic shunting in cirrhotic patients. There was a strong correlation between fasting plasma glucagon concentrations and aspartate transaminase levels (r = 0.68; p < 0.01) in cirrhotic and portal vein block patients. Significant elevations of growth hormone were seen only in cirrhotic patients. It is concluded that hyperglucagonaemia is a feature of hepatocellular damage rather than portal-systemic shunting but the relationship between elevated glucagon and growth hormone concentrations and carbohydrate intolerance in cirrhosis remains unclear.
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PMID:Hyperglucagonaemia in cirrhosis. Relationship to hepatocellular damage. 741 64

This study was designed to investigate the effect of octreotide (Sandostatin, Sandoz), an analogue of somatostatin, on the hemodynamics and glucagon level in portal hypertension. Sixteen portal hypertensive rabbits produced by partial ligation of the portal vein two weeks earlier received an intravenous infusion of octreotide at a dose of 30 micrograms/h. After infusion of octreotide, a significant reduction in portal venous pressure from 16.2 +/- 3.9 mmHg (mean +/- SD) to 13.3 +/- 4.3 mmHg at 21 minutes and 12.0 +/- 4.5 mmHg 42 minutes was noted. A persistent decrease in portal pressure to 11.0 +/- 4.5 mmHg 21 minutes after stopping infusion of octreotide was also observed. Portal venous blood flow was decreased significantly from 60.9 +/- 13.1 mL/min to 46.9 +/- 15.0 ml/min at 21 minutes and to 45.8 +/- 12.8 ml/min at 42 minutes. A slight elevation of portal blood flow to 49.0 +/- 14.1 ml/min was noted 21 minutes after cessation of octreotide infusion. Portal venous resistance was slightly elevated during infusion of octreotide (before infusion: 2.2 +/- 1.4 dyne.s.cm-5, 21 minutes after infusion: 2.4 +/- 1.4 dyne.s.cm-5 and 42 minutes after infusion: 2.3 +/- 1.3 dyne.s.cm-5), and decreased (1.9 +/- 1.0 dyne.s.cm-5, p < 0.1) with a forward significance after stopping infusion. There were no significant changes in systemic arterial pressure during this experiment. A significant decrease (p < 0.05) in glucagon level from 323 +/- 93 pg/dl to 267 +/- 62 pg/dl at 21 minutes and to 298 +/- 88 pg/dl at 42 minutes in the portal vein was noted during the infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of octreotide on hemodynamics and glucagon levels in portal hypertensive rabbits. 785 49

This study was designed to test the hypothesis that deprivation of enteral feeding contributes to the development of total parenteral nutrition (TPN)-induced hepatic dysfunction and that alterations of gut hormones are involved in its pathogenesis. Twenty-one adult Sprague-Dawley rats were randomized into three groups: group 1 received chow feeding ad libitum (288 kcal/kg per day); group 2 received dextrose-based TPN (320 +/- 5 kcal/kg per day); and group 3 received TPN (315 +/- 15 kcal/kg per day) plus chow feeding ad libitum (74 +/- 1 kcal/kg per day). After 7 days, portal blood was assayed for insulin, glucagon, gastrin, peptide YY, secretin, and vasoactive intestinal polypeptide; systemic blood for determination of liver function tests and serum lipid analysis. Liver biopsies were taken for histology and staining for fat, and the remainder of the livers were removed for tissue lipid analysis. TPN induced striking hepatic steatosis with prominent histologic changes and accumulation of lipids, mainly triglycerides and cholesterol ester, in the liver. Addition of enteral feeding to TPN-treated animals significantly reduced the histologic changes as well as lipid accumulation in the liver. Portal plasma levels of gastrin and peptide YY were reduced in animals maintained on TPN alone, with no change in secretin or vasoactive intestinal polypeptide levels. Enteral supplementation increased peptide YY levels in group 3, but not to normal, while gastrin secretion remained decreased. The serum triglyceride levels were decreased in both TPN groups; no differences were detected in the serum cholesterol levels or liver function tests.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of enteral feeding on hepatic steatosis induced by total parenteral nutrition. 816 98

Casein hydrolysate administration to fasted rats resulted in a biphasic response of glycogen synthase. Fifteen minutes after the protein meal, synthase R (active form) was increased. This was associated with a transient increase in hepatic glucose and glucose-6-phosphate (G6P) concentrations. Both glucose and G6P are known to stimulate synthase phosphatase activity, which would result in activation of synthase. Portal plasma insulin concentration was directly related to the amount of synthase R present. By 1 hour after the meal, synthase R activity was decreased compared with the control activity. Hepatic glycogen concentration was variable during the first 30 minutes after the meal, and then decreased progressively. Portal plasma glucagon concentration and phosphorylase a activity were elevated at all time points. The data suggest that the increased portal plasma glucagon concentration is the major hormonal signal for glycogen metabolism during the second hour following a pure protein meal. However, during the first 30 minutes glycogenolysis is attenuated, perhaps due to the transient increase in insulin and an increased intracellular G6P concentration.
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PMID:The effect of oral casein on hepatic glycogen metabolism in fasted rats. 849 22

The effects of catecholamines (CATS) infused into the hepatic portal vein were studied in ten 18-h-fasted conscious dogs. Glucose production (GP) and gluconeogenesis (GNG) were assessed using tracer ([3H]glucose, [14C]alanine) and arteriovenous difference techniques. Each experiment consisted of a 100-min equilibration, a 40-min basal, and two 90-min test periods. A pancreatic clamp (somatostatin + basal portal insulin and glucagon) was used to fix insulin and glucagon at basal levels. Propranolol (1 microgram.kg-1.min-1) and phentolamine (2 micrograms.kg-1.min-1) were infused intraportally during both test periods of the blockade group while a carrier solution was infused in the control group. Norepinephrine (NE; 100 ng.kg-1.min-1) and epinephrine (Epi; 40 ng.kg-1.min-1) were infused intraportally during the second test period of both protocols. Portal NE (70 +/- 46 to 8,404 +/- 674 and 162 +/- 57 to 6,530 +/- 624 pg/ml, respectively) and portal Epi (21 +/- 11 to 3,587 +/- 309 and 29 +/- 6 to 2,989 +/- 406 pg/ml, respectively) rose in the control and adrenergic blockade groups, respectively. The increases in arterial NE and Epi were modest in both groups. Intraportal infusion of CATS increased GP from 2.1 +/- 0.2 to 6.2 +/- 1.0 mg.kg-1.min-1 in the control group but did not change it (2.7 +/- 0.4 to 2.7 +/- 0.3 mg.kg-1.min-1) in the blockade group. Portal CATS had no effect on GNG in the presence or absence of adrenergic blockade (GNG rose from 0.7 +/- 0.2 to 0.9 +/- 0.2 and 0.8 +/- 0.2 to 1.0 +/- 0.2 mg.kg-1.min-1 in the control and blockade groups, respectively). In conclusion, portal infusion of catecholamines significantly augmented GP by selectively stimulating glycogenolysis. The increase in hepatic GP could be completely inhibited by intraportal adrenergic blockade.
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PMID:Direct effects of catecholamines on hepatic glucose production in conscious dog are due to glycogenolysis. 876 90

There is little information concerning the physiological response to hypoglycaemia induced by sulphonylureas. We compared the physiological and symptomatic responses to insulin and tolbutamide induced hypoglycaemia in 8 normal subjects. While infusing either insulin or tolbutamide, we used a glucose clamp to maintain blood glucose at 4.5 mmol l-1 for 30 min and lowered it to 2.9 mmol l-1 for a further 30 min. Mean peripheral insulin levels during the insulin infusion arm in comparison with the tolbutamide infusion were not significantly different during the euglycaemic plateau: 106 +/- 4 vs 77 +/- 15 mU l-1 (mean +/- SEM) (mean difference 29 mU l-1, 95% CI -22 to 80; p = NS) but were greater during the hypoglycaemic plateau: 106 +/- 3.5 vs 21.0 +/- 4.0 mU l-1 (mean difference 85 mU l-1, 95% CI 72 to 98; p < 0.0001). Portal insulin concentrations, calculated from C-peptide data were not significantly different during the euglycaemic plateau with insulin as compared to tolbutamide. However, during hypoglycaemia portal insulin concentrations were significantly higher 15 min from the start of the plateau, during insulin infusion. During hypoglycaemia induced by either insulin or tolbutamide there were similar peak responses of glucagon: 124 +/- 14 vs 128 +/- 7 ng l-1 (mean difference -4, 95% CI -39 to 31; p = NS) and adrenaline: 2.9 +/- 0.4 vs 2.8 +/- 0.3 nmol l-1, (mean difference 0.1, 95% CI -0.9 to 1.0; p = NS). Increases in tremor and sweating and deterioration in reaction time were similar during both periods of hypoglycaemia as were increases in total: 18.5 +/- 1.4 vs 19.6 +/- 2.2 (mean difference -1.0, 95% CI -3.8 to 1.8; p = NS) and autonomic: 8.9 +/- 0.9 vs. 9.9 +/- 1.3 (mean difference -1.1, 95% CI -5.9 to 3.6; p = NS) symptom scores. We conclude that there is no difference in the glucagon, sympathoadrenal, cognitive or symptomatic response during hypoglycaemia induced by either insulin or tolbutamide. This suggests that the different insulin concentrations produced by these contrasting models of hypoglycaemia had no effect on the physiological response and patients taking sulphonylureas can be expected to develop similar warning symptoms to those on insulin.
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PMID:Similar physiological and symptomatic responses to sulphonylurea and insulin induced hypoglycaemia in normal subjects. 884 97

This study was undertaken to determine the impact of portal adrenergic blockade on the gluconeogenic effects of epinephrine (EPI) and norepinephrine (NE). Experiments were performed on 18-hour fasted conscious dogs and consisted of a 100-minute equilibration, a 40-minute basal, and two 90-minute test periods. A pancreatic clamp was used to fix insulin and glucagon levels at basal values. Propranolol (1 microgram/kg.min) and phentolamine (2 micrograms/kg.min) were infused intraportally during both test periods. Portal infusion of alpha- and beta-adrenergic blockers alone (first test period) slightly increased hepatic glucose production from 2.4 +/- 0.4 to 2.8 +/- 0.5 mg/kg.min (nonsignificant [NS]) NE (500 ng/kg.min) and EPI (180 ng/kg.min) were infused peripherally during the second test period. Arterial NE and EPI increased from 186 +/- 63 to 6,725 +/- 913 pg/mL and 76 +/- 25 to 2,674 +/- 344 pg/mL, respectively. Portal NE and EPI increased from 135 +/- 32 to 4,082 +/- 747 pg/mL and 28 +/- 8 to 1,114 +/- 174 pg/mL, respectively. Hepatic glucose production, the maximal gluconeogenic rate, and gluconeogenic efficiency increased from 2.8 +/- 0.5 to 3.8 +/- 0.4 mg/kg.min (P < .05), 0.7 +/- 0.3 to 2.1 +/- 0.6 mg/kg.min (P < .05), and 21% +/- 8% to 60% +/- 13% (P < .05), respectively, in response to catecholamine infusion. Net hepatic lactate balance changed from output (1.5 +/- 3.3 mumol/kg.min) to uptake (-11.0 +/- 3.8 mumol/kg.min, P < .05). Net hepatic glycerol uptake increased from -1.5 +/- 0.7 to -5.5 +/- 2.0 mumol/kg.min (P < .05). Net hepatic uptake of gluconeogenic amino acids did not change significantly. Similarly, hepatic glycogenolysis did not increase during catecholamine infusion. In conclusion, portal delivery of adrenergic blockers selectively inhibits the glycogenolytic effects of EPI and NE on the liver, but allows a marked gluconeogenic response to the catecholamines.
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PMID:Portal adrenergic blockade does not inhibit the gluconeogenic effects of circulating catecholamines on the liver. 910 55

Suppression of endogenous glucose production (EGP) is one of insulin's primary metabolic effects and failure of this action is a major contributor to fasting hyperglycemia of type 2 diabetes mellitus. Classically, insulin was thought to suppress the liver directly, via hyperinsulinemia in the portal vein. Recently, however, we and others have demonstrated that at least part, and possibly most of insulin's action to suppress EGP is normally mediated via an extrahepatic (i.e., indirect) mechanism. We have suggested that this mechanism involves insulin suppression of adipocyte lipolysis, leading to lowered FFA and reduced EGP ("Single Gateway Hypothesis"). Previous studies of the indirect insulin effect from this laboratory were done under conditions of lowered portal glucagon. Because of the possibility that the direct (i.e., portal) effect of insulin may have been underestimated with hypoglucagonemia, these studies examined the relative importance of portal insulin, versus peripheral insulin (administered at one-half the dose to equalize peripheral insulin levels) at four rates of portal glucagon infusion: 0, 0.65 (under-), 1.5 (basal-), and 3.0 ng/kg per min (over-replacement). Portal versus peripheral insulin suppressed steady-state EGP to the same extent (52%), confirming that the primary effect of insulin to suppress EGP is via the peripheral mechanism. This conclusion was maintained regardless of portal glucagonemia, although there was some evidence for an increase in the direct insulin effect at hyperglucagonemia. The indirect effect of insulin is the primary mechanism of steady-state EGP suppression under normal conditions. The direct effect increases with hyperglucagonemia; however, the indirect effect remains predominant even under those conditions.
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PMID:Indirect effect of insulin to suppress endogenous glucose production is dominant, even with hyperglucagonemia. 939 59

Our aim was to assess hepatic and gut catecholamine clearance under normal and simulated stress conditions. Following a 90-minute saline infusion period, epinephrine ([EPI] 180 ng/kg x min) and norepinephrine ([NE] 500 ng/kg x min) were infused peripherally for 90 minutes into five 18-hour fasted, conscious dogs undergoing a pancreatic clamp (somatostatin plus basal insulin and glucagon). Arterial plasma levels of EPI and NE increased from 44 +/- 9 to 2,961 +/- 445 and 96 +/- 6 to 6,467 +/- 571 pg/mL, respectively (both P < .05). Portal vein plasma levels of EPI and NE increased from 23 +/- 8 to 1,311 +/- 173 and 79 +/- 10 to 3,477 +/- 380 pg/mL, respectively (both P < .05). Hepatic vein plasma levels of EPI and NE increased from 5 +/- 2 to 117 +/- 33 and 48 +/- 10 to 448 +/- 59 pg/mL, respectively (both P < .05). Net hepatic and gut EPI uptake increased from 0.5 +/- 0.1 to 30.0 +/- 3.0 and 0.4 +/- 0.1 to 26.3 +/- 4.0 ng/kg x min, respectively (both P < .05). Net hepatic and gut NE uptake increased from 1.5 +/- 0.4 to 74.7 +/- 8.4 and 0.8 +/- 0.2 to 57.9 +/- 7.6 ng/kg x min, respectively (both P < .05). Neither the net hepatic (0.86 +/- 0.05 to 0.93 +/- 0.02) nor gut (0.45 +/- 0.10 to 0.55 +/- 0.04) fractional extraction of EPI changed significantly during the simulated stress condition. Net hepatic and gut spillover of NE increased from 0.8 +/- 0.2 to 3.5 +/- 1.3 and 0.6 +/- 0.2 to 8.8 +/- 2.0 ng/kg x min, respectively, during catecholamine infusion (both P < .05). These results indicate that (1) approximately 30% of circulating catecholamines are cleared by the splanchnic bed (16% and 14% by the liver and gut, respectively); (2) the liver and gut remove a large proportion (approximately 86% to 93% and 45% to 55%, respectively) of the catecholamines delivered to them on first pass; and (3) high levels of plasma catecholamines increase NE spillover from both the liver and gut, suggesting that the percentage of NE released from the presynaptic neuron that escapes the synaptic cleft is increased in the presence of high circulating catecholamine levels.
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PMID:Hepatic and gut clearance of catecholamines in the conscious dog. 1002 92


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