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)

An abrupt reduction of medium osmolarity by as little as 20 mosM evoked a discrete short-lived insulin secretory response from perifused chopped pancreas or isolated islets. The insulin response occurred earlier than that induced by either glucose or tolbutamide. None of the usual modifiers of insulin secretion significantly altered this secretory response. Glycolytic inhibitors, adrenergic agonists and blocking agents, cholinergic blocking agents, mitotic spindle inhibitors, and agents influencing sodium pump activity failed to alter hyposmolar-induced insulin secretion. Manipulation of the perifusion medium calcium concentration was the only procedure tested that influenced the secretory response. Perturbations of medium calcium concentration that increased the tissue-to-medium calcium gradient augmented the hyposmolar-induced insulin response and those that decreased tissue-to-medium calcium gradient greatly inhibited the response. The precise cause of the insulin response to a decrease in bathing fluid osmolarity remains undefined; however, the stimulus is not specific for insulin because increases in glucagon and amylase were also elicited by the hyposmolar stimulus.
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PMID:An effect of hyposmolarity on insulin release in vitro. 111 35

The catalytic alpha-subunit of rat hepatic (Na+, K+)-ATPase (EC 3.6.1.3) has been isolated by immunoaffinity chromatography from microsomes solubilized in n-dodecyl octaethylene glycol monoether. The procedure employs an anticatalytic mouse monoclonal antibody ("9-A5") covalently linked to Sepharose 4B that specifically blocks phosphorylation of the sodium pump's alpha-subunit from [gamma-32P]ATP [Schenk, D. B., Hubert, J.J., & Leffert, H.L. (1984) J. Biol. Chem. 259, 14941-14951]. The hepatic subunit is virtually identical with purified rat, dog, and human renal alpha-subunits as judged by its apparent molecular weight after polyacrylamide gel electrophoresis in sodium dodecyl sulfate (Mr 92K) and its two-dimensional tryptic and chymotryptic peptide maps on cellulose-coated thin-layer plates. In contrast, the structures of authentic renal beta-subunits from the three species differ significantly from each other as judged by their peptide maps; no detectable homologies are seen between their chymotryptic maps and those of putative hepatic "beta"-subunits (Mr 50K and 55K) eluted from 9-A5-Sepharose. Additional studies of ouabain-sensitive 86Rb+ uptake in primary cultures of adult rat hepatocytes reveal inhibition curves with single inflection points (ID50 = 0.1 mM ouabain) in the absence or presence of pump-stimulating peptides like insulin, glucagon, and epidermal growth factor. These findings indicate that rat hepatocytes express only one of two known structurally conserved forms of catalytic subunit (the renallike alpha form) and, if at all, structurally divergent forms of the sodium pump's beta-subunit. In addition, immunoaffinity chromatography with 9-A5-Sepharose facilitates the isolation of (Na+, K+)-ATPases from nonrenal tissues with low levels of sodium pumps.
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PMID:Rat hepatic (Na+, K+)-ATPase: alpha-subunit isolation by immunoaffinity chromatography and structural analysis by peptide mapping. 301 14

1. Insulin secretion from pieces of rabbit pancreas incubated in vitro was studied in media of different ionic composition and in response to different substances added to the media.2. Experiments were performed which demonstrated that a sodium pump played a role in insulin secretion and that inhibition of the pump by ouabain, or by the omission of extracellular potassium, stimulated insulin secretion.3. A rise in extracellular potassium concentration stimulated insulin secretion independently of changes in the osmolarity or sodium or chloride concentration of the incubation medium.4. The role of extracellular sodium in insulin secretion was investigated. Extracellular sodium was a pre-requisite for insulin secretion stimulated by glucose, glucagon, L-leucine, tolbutamide, potassium or ouabain.5. The presence of 3.3 mM glucose in the incubation medium was not essential for the stimulation of insulin secretion by L-leucine, tolbutamide or ouabain. Glucagon did not stimulate insulin secretion in the presence of 3.3 mM glucose but did so in the presence of 16.5 mM glucose.6. The results obtained in these experiments suggested that a transmembrane sodium flux probably in the beta cell was a fundamental event in the stimulation of insulin secretion by diverse stimuli.
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PMID:The role of sodium and potassium in insulin secretion from rabbit pancreas. 563 96

Profound metal-related changes in the supply of metabolites to t he liver and in the hepatic metabolism occur, and there is ample evidence that neural signals from hepatic metabolic sensors can affect eating. Hepatic afferent nerves presumably represent glucosensors which contribute to the control of eating by monitoring their own glucose utilization. Yet, the nature of the putative sensors that respond to the oxidation of other metabolites than glucose had not been identified. ATP and sodium pump activity may link hepatic oxidative metabolism and membrane potential, because hepatic phosphate-trapping by 2,5-anhydro-mannitol, and inhibition of sodium pump activity by ouabain is associated with a stimulation of eating. Hepatocyte membrane potential is also subject to changes in transmembranal potassium flow through volumetrically controlled membranal potassium channels. Yet it is unknown if and how hepatocytes are linked to afferent nerves. It is also unclear how the effects of glucagon and insulin fit into the hepatic metabolic control of eating. Glucagon appears to induce satiety through its actions in the liver, but the involved mechanism is still unclear. Recent studies suggest that insulin, which has mainly been explored as a centrally acting long-term satiety signal, has an immediate effect on meal size, but is presently unknown whether an hepatic action of insulin is involved.
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PMID:Role of the liver in the metabolic control of eating: what we know--and what we do not know. 862 21