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)

1. The helospectins are peptides structurally related to helodermin, vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI) and secretin, which all potently stimulate glucagon secretion in the mouse. Therefore, the effects of helospectin I (0.1-0.8 nmol kg-1) on insulin and glucagon secretion under basal conditions and after stimulation with glucose (2.8 mmol kg-1) or the cholinoceptor agonist, carbachol (0.16 mumol kg-1), were examined in vivo in the mouse. 2. Helospectin I potently increased plasma levels of glucagon after its intravenous injection in mice. The increase was observed after only 2 min, and was evident also after 6 min. 3. In contrast, plasma insulin levels were not altered by helospectin I after 2 min, but slightly increased after 6 min. Plasma glucose levels were not altered by the peptide. 4. Carbachol-induced glucagon secretion was markedly potentiated by helospectin I. In contrast, glucose- or carbachol-stimulated insulin secretion was not affected by the peptide. 5. In conclusion, helospectin I markedly stimulates glucagon secretion in the mouse whereas the peptide has no direct action on insulin secretion. This pattern of effect of helospectin I is similar to that previously reported for helodermin, VIP, PHI and secretin in the mouse, i.e., for all peptides belonging to this superfamily of peptides.
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PMID:Effects of helospectin I on insulin and glucagon secretion in the mouse. 185 19

The release of insulin, glucagon, somatostatin and pancreatic polypeptide (PP) by isolated mouse pancreatic islets was determined during 30-min incubations at 5.6 and 16.7 mmol glucose/l in the absence and presence of gastric inhibitory polypeptide (GIP), vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI) at concentrations of 1-1000 nmol/l. Insulin release was enhanced (greater than 50%) by GIP (100-1000 nmol/l) and VIP (1 mumol/l) at 5.6 mmol glucose/l, but not at 16.7 mmol glucose/l. Glucagon release was increased by GIP (100-1000 nmol/l), and by VIP and PHI (1-1000 nmol/l) at both glucose concentrations in a dose-related manner (maximum increases greater than tenfold). Somatostatin release was similarly increased by GIP (10-1000 nmol/l) at both glucose concentrations. Only the highest concentration (1 mumol/l) of PHI tested increased somatostatin release (twofold) at 5.6 mmol glucose/l, whereas PHI and VIP (1-1000 nmol/l) reduced (greater than 37%) somatostatin release at 16.7 mmol glucose/l. PP release was increased (49-58%) by 100-1000 nmol GIP/l, but was not significantly altered by VIP, and was reduced (39-56%) by PHI. The results indicate that GIP, VIP and PHI each stimulate glucagon release in a dose-related manner, but they exert discretely different effects on other islet hormones depending upon the dose and the prevailing glucose concentration.
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PMID:Effects of gastric inhibitory polypeptide, vasoactive intestinal polypeptide and peptide histidine isoleucine on the secretion of hormones by isolated mouse pancreatic islets. 197 1

Both albuminuria (UalbV) and albumin synthesis (AlbSyn) are modulated by dietary protein in nephrotic rats, but the agent(s) linking diet to altered UalbV and AlbSyn is unknown. Others have reported that branched-chain amino acids (BCAA) cause neither increased renal blood flow nor glomerular filtration rate (GFR) normally induced by dietary protein nor increased blood glucagon thought to be necessary for protein-mediated effects on renal hemodynamics. The effect of BCAA on UalbV is unknown. Because BCAA increase AlbSyn in tissue culture and after a fast, it is possible that feeding BCAA may increase AlbSyn but not UalbV in nephrosis. Nephrotic rats were fed either 8.5% casein (LP); 21% casein (NP); 8.5% casein supplemented with valine, leucine, and isoleucine to the total amount provided by a 21% casein diet (2.37%) (LBC); or 8.5% casein plus 12.5% BCAA providing a diet isonitrogenous to 21% casein (HBC). UalbV and AlbSyn were significantly greater in NP compared with LP, LBC, or HBC and were the same in the latter three groups. Glucagon was infused into nephrotic rats fed 8.5% casein either subcutaneously or intraperitoneally in quantities sufficient to increase plasma levels to over 10 times control but had no effect on UalbV. The ability of dietary protein to increase AlbSyn or UalbV is not a result of total alpha-amino nitrogen intake but is a result of the specific amino acid composition of the diet and must result entirely from the effect of one or more non-BCAA. Increased blood glucagon alone has no effect on UalbV.
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PMID:Branched-chain amino acids augment neither albuminuria nor albumin synthesis in nephrotic rats. 199 10

Localization and pharmacological properties of vasoactive intestinal peptide (VIP) binding sites were investigated in eyes from albino rabbits and rats using an in vitro autoradiographic method. [125I]VIP was used as ligand, and various unlabelled peptides were studied to test the specificity of binding. Autoradiograms were generated by apposing 20-microns-thick cryostat eye sections to [3H]Hyperfilm or autoradiographic emulsion and quantified by means of image analysis procedures. Specific binding represented about 85% of total binding. Kinetic studies showed that equilibrium was reached after a 120-min incubation at room temperature. Biochemical investigations demonstrated that [125I-]VIP bound to a population of sites with high affinity (Kd = 2.27 +/- 0.25 nM). Inhibition of [125I]VIP binding with VIP and related peptides indicated the following rank order of potency: VIP greater than Peptide histidine isoleucine greater than secretin greater than human growth hormone-releasing factor, glucagon, VIP1-14, VIP14-28. In both species, specific binding was found in conjunctiva, iris, ciliary processes, choroid and retina. Moderate grain densities of VIP binding sites were also present in the rat cornea. Quantitative analysis of the autoradiograms revealed that the highest densities of [125I]VIP binding sites were located in the iris and ciliary epithelia in rabbits and in the inner retina in rats. Our findings suggest that VIP may play an important role in several ocular functions, especially in aqueous humor dynamics and retinal neuromodulation.
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PMID:Autoradiographic characterization and localization of vasoactive intestinal peptide binding sites in albino rat and rabbit eyes. 201 64

Vasoactive intestinal peptide (VIP) has been implicated as a physiological PRL-releasing factor; however, characterization of VIP receptors on normal pituitaries using radioligand-binding methods has been problematic. In this study we demonstrated specific receptors for VIP in anterior pituitary glands of female rats using HPLC-purified monoiodinated [Tyr(125I)10]VIP. Binding of VIP was reversible, saturable to receptor and radioligand, regulated by guanine nucleotides, and dependent on time and temperature. Scatchard analysis of competitive binding studies indicated high and low affinity binding sites, with equilibrium dissociation constants (Kd) of 0.19 +/- 0.03 and 28 +/- 16 nM, respectively. The corresponding maximum numbers of binding sites were 158 +/- 34 fmol/mg and 11.7 +/- 6.9 pmol/mg. Binding was specific, as peptides with structural homology to VIP were less than 100th as potent as VIP. The rank order of potency of the peptides tested was VIP greater than rat (r) peptide histidine isoleucine = human (h) PHI greater than rGRF greater than bovine GRF = porcine PHI = VIP-(10-28) greater than hGRF greater than secretin greater than apamin greater than glucagon. Radioligand binding was associated primarily with lactotrope-enriched fractions prepared by unit gravity sedimentation of dispersed anterior pituitary cells. VIP stimulated PRL release from cultured rat anterior pituitary cells, with an ED50 of 1 nM. These results, comprising the first identification of specific VIP receptors in normal rat anterior pituitary tissue using radioligand-binding methods, provide additional support for a biological role of VIP in lactotrope function.
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PMID:Receptors for vasoactive intestinal peptide in rat anterior pituitary glands: localization of binding to lactotropes. 215 75

Specific 125I-labelled vasoactive intestinal peptide (VIP) binding was determined in feline renal cortical and medullary plasma membranes. For the cortex, Scatchard analysis of the data resulted in a curvilinear plot with a high-affinity site K0.5 of 8.4 +/- 2.6 nmol l-1 (SE, n = 6) and a second low-affinity site K0.5 204 +/- 16 nmol l-1 with binding site concentrations (Bmax) of 385 +/- 44.5 and 2710 +/- 181.3 fmol mg protein-1 respectively. Conversely a similar analysis of the results obtained for outer medullary membranes gave a single site with a K0.5 of 1.2 +/- 0.2 nmol l-1 (SE, n = 4) and Bmax of 157.8 +/- 24.7 fmol mg-1. Inner medullary membrane binding data. Gave a single site of lower affinity (K0.5 = 62.5 +/- 21.6 nmol l-1; n = 3). Structurally related peptides, glucagon and secretin, were ineffective (up to 1 mumol l-1) in displacing VIP from specific sites in both cortex and medulla. Porcine PHI 1-27 (a peptide having N-terminal histidine and C-terminal isoleucine) and a VIP antagonist [4-Cl-D-Phe6Leu17]VIP both displaced 125I-VIP from cortical and medullary membrane binding sites with IC50 values of 43.0 nmol l-1 and 1.3 mumol l-1 (cortex) and 132.0 nmol l-1 and 1.5 mumol l-1 (medulla) respectively. The localisation of specific VIP binding sites in feline kidney was investigated further by in vitro autoradiography.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Localisation and characterisation of functional vasoactive intestinal peptide receptors in feline kidney. 216 36

The vasoactive intestinal peptide (VIP) receptors were identified on the membranes from the rat anterior pituitary gland with [125I]VIP. The dissociation constant (Kd) and the maximal binding capacity (Bmax) values were estimated from the competitive inhibition data. The Kd and Bmax values were 1.05 +/- 0.75 nM and 103 +/- 11 fmol/mg protein, respectively. The order of molar potency of related peptides to inhibit [125I]VIP binding was VIP greater than peptide histidine isoleucine (PHI) greater than secretin greater than glucagon. Glucagon was not effective to inhibit the binding. [125I]VIP binding was effectively inhibited by the addition of guanine nucleotides. The order of molar potency to inhibit the binding was Gpp(NH)p greater than GTP greater than GDP greater than GMP greater than ATP. These results directly suggest the coupling of VIP receptors with guanine nucleotide binding proteins in the anterior pituitary gland.
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PMID:Direct demonstration of guanine nucleotide sensitive receptors for vasoactive intestinal peptide in the anterior lobe of the rat pituitary gland. 216 81

Fasting concentrations, clearance of exogenous infused amino acids, and lean body mass were studied in a patient with glucagonoma syndrome (fasting glucagon = 380 pmol/l, normal range 15-45 pmol). The fasting concentrations of all amino acids were reduced. The clearances of alanine, arginine, glycine, isoleucine, leucine, lysine, methionine, proline, serine, threonine, and tyrosine were increased. The urea synthesis rate during amino acid infusion was 27 mumols/kg per minute (normal range 20-24 mumols/kg per minute). The lean body mass of the patients was reduced to 59% of the expected value. It is suggested that the weight loss of patients with glucagonoma syndrome is partly due to increased hepatic conversion of amino acid nitrogen to urea nitrogen, resulting in decreased blood amino acid concentration, and secondary to this, organ protein catabolism, as shown by the decreased lean body mass.
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PMID:Increased amino acid clearance and urea synthesis in a patient with glucagonoma. 216 78

Despite its name, Vasoactive Intestinal Peptide (VIP), a 28-amino acid peptide, is widely distributed in the eye where it is thought to play a physiological role, particularly in aqueous humor dynamics or retinal neurotransmission. Localization and pharmacological properties of VIP binding sites were investigated in eyes from albino rabbit and rat using an in vitro autoradiographic method. 125I-VIP was used as ligand and unlabelled VIP was used to displace labelled VIP. Autoradiograms were generated by apposing the slides to 3H-Ultrofilm or autoradiographic emulsion and analysed using an image analysis system. Specific binding represented about 85% of total binding. Kinetic studies showed that equilibrium was reached after 140 min incubation at room temperature. Biochemical investigations demonstrated that 125I-VIP bound to a population of sites with high affinity (Kd = 2.95 +/- 0.5 nM). Inhibition of 125I-VIP binding with VIP and related peptide gave a rank order of potency: VIP greater than peptide histidine isoleucine greater than secretin greater than human growth hormone-releasing factor, glucagon, VIP1-14, VIP14-28. In both species, specific binding were found in conjunctiva, iris, ciliary processes, choroid and retina. Quantitative analysis of autoradiograms revealed that the highest densities of binding sites were localized in the ciliary epithelium in rabbits and in the inner retina in rats.
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PMID:[Autoradiographic localization and characterization of the ocular binding sites of the VIP (vasoactive intestinal peptide) in albino rats and rabbits]. 217 30

The ileocaecal junctions of 5 horses and 2 donkeys were examined by using antisera to the following peptides: somatostatin, glucagon, gastrin, neurotensin, vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI), calcitonin gene-related peptide (CGRP), substance P (SP) and neuropeptide Y (NPY). Antisera to somatostatin, neurotensin and NPY demonstrated endocrine cells in the ileal- and caecal parts of the ileocaecal junction, while immunoreactivity for glucagon was demonstrated in endocrine cells of the ileal part only. Nerve cell bodies showing immunoreactivity to SP, VIP, CGRP and PHI were demonstrated in the myenteric and submucosal plexuses and were associated with small blood vessels in the submucosa of all the regions tested. Ramified nerve fibres in the submucosa immunoreactive to SP, VIP, CGRP and PHI extended to the mucosa and to small blood vessels in the submucosa. Nerve fibres showing immunoreactivity to SP, VIP and PHI extended to the circular smooth muscle layer of the ileocaecal junction.
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PMID:An immunohistochemical study of various peptide-containing endocrine cells and neurones at the equine ileocaecal junction. 233 94


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