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)

In the isolated perfused rat liver, glucagon increased glucose, cAMP, and bile production. Secretin increased cAMP in the effluent more and bile volume less than glucagon, but did not increase glucose output. When glucagon and secretin were infused together, the effect on cAMP was additive, but glucose output and bile volume were the same as with glucagon alone. The stimulation of bile production by glucagon was suppressed by phenylephrine but not by oxymetazoline, whereas the glucagon-induced cAMP increase in the effluent was suppressed by oxymetazoline in a dose-dependent manner, but not by phenylephrine. Glucagon-stimulated glucose output was not suppressed even when cAMP in the effluent was significantly suppressed by oxymetazoline. The secretin-induced stimulation of bile production was suppressed by phenylephrine, but not by oxymetazoline. Secretin-stimulated cAMP was suppressed more by oxymetazoline than by phenylephrine. The bile volume was not suppressed by phenylephrine alone either in the presence or in the absence of sodium taurocholate. These results indicate that the cholestatic effect of adrenergic agents is mediated by alpha 1-adrenergic receptors, whereas their cAMP suppressive effect is mediated by alpha 2-adrenergic receptors. The stimulatory effect of glucagon on cAMP production was more resistant to alpha-adrenergic agonists than to that of secretin. The dissociation by oxymetazoline of the effects of glucagon on cAMP production from its effect on glucose production is unexplained, whereas the significance of the secretin-induced increase in cAMP production is uncertain.
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PMID:Dissociation of the alpha-adrenergic inhibitory effects on glucagon- and secretin-stimulated bile volume and on cyclic adenosine monophosphate production in the isolated perfused rat liver. 285 88

Using isolated perfused rat liver, the direct effect of secretin, glucagon, caerulein, insulin and somatostatin on choleresis was investigated. When the liver was perfused in the absence of sodium taurocholate, the bile volumes were: control, 0.33 +/- 0.01 (mean +/- S.E.M.) ml/10 g liver per 50 min; secretin 0.05 U/ml, 0.39 +/- 0.01 (P less than 0.01); glucagon 10(-10) M, 0.44 +/- 0.02 (P less than 0.01); caerulein 10(-8) M, 0.34 +/- 0.03 (n.s.); insulin 1 mU/ml, 0.35 +/- 0.02 (n.s.); glucagon plus somatostatin 10(-7) M, 0.46 +/- 0.03 (n.s. vs. glucagon alone), respectively. When 10(-5) M sodium taurocholate was present in the perfusate, the bile volumes were: control, 0.61 +/- 0.03; secretin, 0.63 +/- 0.01 (n.s.); glucagon, 0.70 +/- 0.01 (P less than 0.05); caerulein, 0.55 +/- 0.01 (n.s.); insulin, 0.62 +/- 0.04 (n.s.); somatostatin, 0.59 +/- 0.01 (n.s.); respectively. Glucagon increased glucose output and cyclic AMP in the effluent from the liver neither of which were suppressed by somatostatin. Secretin increased cyclic AMP but not glucose output. These results indicate that glucagon has the most potent action on bile acid-independent canalicular bile, that caerulein and insulin do not act on canalicular bile production directly and that somatostatin does not directly suppress canalicular bile production nor hepatic glucose output produced by glucagon in rats.
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PMID:Effect of gastrointestinal hormones on choleresis from the isolated perfused rat liver. 285 40

Preganglionic nerve stimulation leads to an acute elevation of tyrosine hydroxylase (TH) activity in the rat superior cervical ganglion. This effect is mediated in part by acetylcholine, acting via nicotinic receptors, and in part by a noncholinergic neurotransmitter. As a first step in an attempt to identify this noncholinergic transmitter, we have examined a number of biogenic amines, purine nucleotides, neuropeptides, and other compounds for their ability to increase TH activity. Secretin, vasoactive intestinal peptide (VIP), and PHI (a 27-amino acid peptide with an NH2-terminal histidine and a COOH-terminal isoleucine amide), all members of the secretin family of peptides, increased TH activity acutely. Human pancreatic growth hormone-releasing factor, glucagon, and gastric inhibitory peptide (three other members of this peptide family) and all other transmitter candidates tested had no effect on this enzyme activity. We have examined the possibility that this peptidergic regulation of TH activity is mediated via changes in adenosine 3',5'-cyclic monophosphate (cAMP) levels. When the six members of the secretin family were tested for their ability to increase cAMP levels in the ganglion, secretin, VIP, and PHI significantly increased this cyclic nucleotide, whereas growth hormone-releasing factor, glucagon, and gastric inhibitory peptide produced no significant effects. The rank orders of potency and of efficacy of secretin, VIP, and PHI in altering TH activity and cAMP levels were identical. Furthermore, a strong correlation was found between the cAMP level and the TH activity in individual ganglia exposed to these peptides. Finally, 8-bromoadenosine 3',5'-cyclic monophosphate and forskolin also increased TH activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of the concentration of adenosine 3',5'-cyclic monophosphate and the activity of tyrosine hydroxylase in the rat superior cervical ganglion by three neuropeptides of the secretin family. 286 28

The blood flow of the alimentary tract in anesthetized dogs was measured with radioactively labeled 15-micron microspheres before and after i.v. application of the gastrointestinal hormones glucagon, vasoactive intestinal polypeptide (VIP), secretin, and somatostatin. After 5 min glucagon in a dose of 75 micrograms/kg bolus + 5 micrograms/kg X min-1 infusion increased significantly the blood flow in liver, stomach, duodenum, jejunum, ileum, and colon as well as the cardiac output by 160%, 761%, 662%, 576%, 817.3%, 320%, and 108%, respectively. A dose of 3 ng/kg X min-1 resulted in reduction of the circulation in liver, gastric fundus, duodenum, and colon by 27.7%, 19.1%, 16.2%, and 10.7% after 5 min while the cardiac output was not affected. Vasoactive intestinal polypeptide (VIP) infused in a dose of 3.3 pmol/kg X min-1 for 5 min increased the blood flow in the pancreas by 30% and reduced it in the spleen and gastric corpus by 26.9% and 41.5%, respectively. Secretin, another member of the glucagon family, after a 5-min infusion of a dose of 0.5 CU/kg X min-1 increased the cardiac output by 49.96% and the renal circulation by 120.7%. In the gastrointestinal tract circulation of the gastric antrum was stimulated by 474%, of the duodenum by 93.5% and of the ileal mucosa by 178%. Infusion of the pancreatic hormone somatostatin (3.5 micrograms/kg bolus followed by infusion of 3.5 micrograms/kg X h-1) increased the blood flow in the liver by 13%, in the pancreas by 23.15%, and in the spleen by 29.8%, while it reduced it in the fundic mucosa by 17.1% and corpus mucosa by 28.8%. In summary, the gastrointestinal hormones examined exert marked and distinct effects on the circulation of the gastrointestinal tract, each hormone in different parts of the digestive tract. Thus, the local microcirculation of the gastrointestinal tract seems to be subject to hormonal in addition to nerval control.
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PMID:Differential effects of gastrointestinal hormones on the blood flow of the alimentary tract of the dog. 287 7

The effects of various biologically active peptides on net jejunal water and electrolyte fluxes were studied in dogs in vivo. Vasoactive intestinal peptide (VIP), gastric inhibitory polypeptide (GIP), glucagon, gastrin, bombesin and neurotensin all had secretagogue activity, while methionine enkephalin stimulated net absorption. Somatostatin had no effect on net basal water and electrolyte transport, but inhibited glucagon-stimulated secretion. Secretin, calcitonin, substance P and pancreatic polypeptide (PP) did not have any effect on net water and electrolyte transport in the doses used in these experiments. The precise role played by these peptides in the control of intestinal transport has still to be determined. Studies in man have confirmed that food in the proximal small bowel stimulates secretion at sites remote from the application of food, and abnormal secretion of some peptides (e.g. VIP) has been associated with diarrhoea. Somatostatin has been used successfully to reduce the volume of certain types of secretory diarrhoea. Methods used in these experiments have been applied to the study of the composition and absorption characteristics of solutions used for oral rehydration in diarrhoea and in exercise-induced dehydration. Glucose polymers have been shown to be absorbed as rapidly as glucose from the jejunum.
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PMID:The effect of luminal and hormonal factors on small intestinal water and electrolyte transport. 287 15

The binding of 125I-vasoactive intestinal peptide (125I-VIP) and 125I-insulin has been examined in highly enriched populations of rat hepatocytes and hepatic nonparenchymal cells. 125I-VIP bound to high-affinity sites (Ka = 1.7 X 10(9) M-1) in nonparenchymal cells. Specific binding in these cells was nearly fivefold greater than in hepatocytes (15.0 +/- 0.6% vs. 3.6 +/- 0.7% radioactivity bound per 4 X 10(5) cells). In contrast, 125I-insulin binding was similar in both cell populations (18.2 +/- 2.4% per 4 X 10(5) cells in hepatocytes vs. 17.1 +/- 1.0% in nonparenchymal cells). Glucagon and insulin had no effect on 125I-VIP binding in nonparenchymal cells. Secretin inhibited 125I-VIP binding but was only about 1% as potent as unlabeled VIP. VIP had no apparent effect on cAMP levels in either cell population, whereas glucagon increased cAMP levels in both cell types. Our findings suggest that VIP binds preferentially to hepatic nonparenchymal cells and that these cells are primarily responsible for the clearance of VIP from the portal circulation.
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PMID:Preferential binding of vasoactive intestinal peptide to hepatic nonparenchymal cells. 298 43

The binding of vasoactive intestinal peptide (VIP) and stimulation of adenylate cyclase were studied in bovine thyroid plasma membranes. The binding depended on time, temperature and was saturable and specific. Binding studies suggested the presence of two classes of binding sites: a class with high affinity (Kd = 13 nM) and low capacity (6411 sites/pg), and a class with low affinity (Kd = 480 nm) and high capacity (105,300 sites/pg) at 15 degrees C. Secretin, glucagon, insulin and somatostatin did not displace the tracer from the membranes. VIP stimulated cyclic AMP production. Maximal cyclic AMP production (2-fold above basal values) was observed with 100 nM VIP and half-maximal response was obtained at 5 nM VIP at 15 degrees C.
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PMID:The interaction of vasoactive intestinal peptide (VIP) with isolated bovine thyroid plasma membranes. 298 35

Receptors for vasoactive intestinal peptide (VIP) have been characterized in rat lymphoid cells. The interaction of [125I] VIP with blood mononuclear cells was rapid, reversible, specific and saturable. At apparent equilibrium, the binding of [125I] VIP was competitively inhibited by native VIP in the 0.01-100 nM range concentration. The binding data were compatible with the existence of two classes of receptors: a high-affinity class with a Kd = 0.050 +/- 0.009 nM and a low binding capacity (2.60 +/- 0.28 fmol/10(6) cells), and a low-affinity class with a Kd = 142 +/- 80 nM and a high binding capacity (1966 +/- 330 fmol/10(6) cells). Secretin, glucagon, insulin and somatostatin did not show any effect at a concentration as high as 100 nM. With spleen lymphoid cells, stoichiometric studies were performed. The binding data were compatible with the existence of two classes of receptors: a high-affinity class with a Kd = 0.100 +/- 0.033 nM and a low binding capacity (4.60 +/- 1.07 fmol/10(6) cells), and low-affinity class with a Kd = 255 +/- 110 nM and high binding capacity (2915 +/- 1160 fmol/10(6) cells). With thymocytes, no binding was obtained under different conditions.
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PMID:Interaction of vasoactive intestinal peptide (VIP) with rat lymphoid cells. 301 77

The structural requirements for VIP interaction with receptors on synaptosomes from rat cerebral cortex was investigated by the ability of VIP and VIP fragments, secretin analogues and fragments, peptides of the VIP/secretin family and several other regulatory peptides to inhibit specific 125I-VIP binding. Only large VIP fragments interacted with the VIP receptors with potencies relative to VIP ranging from 0.9-0.006%. The rank order of inhibition was: VIP 7-27 greater than VIP 11-28 greater than VIP 1-22-NH2 greater than VIP 16-28. Shorter fragments: VIP 18-28; VIP 18-28-NH2; VIP 19-28; VIP 21-28; VIP 22-28; VIP 1-18; VIP 1-18-NH2; VIP 1-10-NH2; VIP 1-6; VIP 16-20 and VIP 16-19 had no effect. Secretin fragments and analogues inhibited 125I-VIP binding with potencies of 2.2-0.01% relative to VIP in the order; secretin greater than (Ala4, Val5) secretin greater than (D-Ala4) secretin greater than (D-Phe6) secretin greater than secretin 5-27 greater than secretin 14-27. Other peptides of the VIP/secretin family inhibited 125I-VIP binding with potencies of 200-1%; avian VIP greater than porcine VIP greater than PHI = secretin greater than human GRF, whereas glucagon and GIP showed no inhibition. Among twenty-five other regulatory peptides only avian PP and somatostatin were inhibitors with relative potencies of 0.02% and 0.03%, respectively. In conclusion it may be emphasized that the intact VIP molecule is essential for VIP interaction with its receptors in the rat brain cortex.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:VIP binding sites on synaptosomes from rat cerebral cortex: structure-binding relationship. 301 96

Vasoactive intestinal peptide (VIP) has been identified in ovarian nerves and stimulates steroid secretion from immature ovaries. To gain insight into its mechanism of action, the effect of VIP on the synthesis of the cholesterol side-chain cleavage enzyme complex was studied in ovarian granulosa cells from immature estrogen-primed rats. The cells were cultured for 48 hr in serum-free medium; the proteins were labeled with [35S]methionine; and the synthesis of cytochrome P-450, iron-sulfur protein, and NADPH:iron-sulfur protein reductase was evaluated by electrophoretic analysis after immunoisolation with polyclonal antibodies directed against the bovine adrenal enzymes. VIP at concentrations ranging from 0.001 to 1 microM stimulated 3- to 5-fold the synthesis of cytochrome P-450 and iron-sulfur protein. Peptide NH2-terminal histidine, COOH-terminal isoleucine, which has greater than 50% sequence homology of VIP, stimulated the synthesis of both proteins at approximately 50% of VIP effectiveness. Secretin, another member of the glucagon-secretin family of peptides, which has only 30% sequence homology to VIP, was without effect. Similar results were observed with the NADPH:iron-sulfur protein reductase. VIP-induced synthesis of the cholesterol side-chain cleavage enzyme complex was accompanied by a dose-related increase in cAMP accumulation and progestin formation. It is concluded that VIP regulates the synthesis of the ovarian cholesterol side-chain cleavage enzyme complex, which catalyzes the rate-limiting reaction in progesterone biosynthesis, and that the VIP effect is at least partially mediated through cAMP. It is suggested that a stimulatory action of VIP on the synthesis of ovarian progesterone may contribute to regulating the functional development of the ovary.
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PMID:Vasoactive intestinal peptide induces the synthesis of the cholesterol side-chain cleavage enzyme complex in cultured rat ovarian granulosa cells. 302 May 46


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