IONIC EFFECTS ON THE UPTAKE OF CHLOROMERCURIBENZENE-p-SULPHONIC ACID BY PANCREATIC ISLETS

1977 ◽  
Vol 86 (3) ◽  
pp. 552-560 ◽  
Author(s):  
Monica Söderberg ◽  
Inge-Bert Täljedal
Keyword(s):  
Pancreatic Islets ◽  
Islet Cell ◽  
Choline Chloride ◽  
Inorganic Ions ◽  
Sulphonic Acid ◽  
Cell Uptake ◽  
Β Cells ◽  
Sulphydryl Groups ◽  
Microdissected Pancreatic Islets ◽  
Ionic Effects

ABSTRACT Effects of inorganic ions on the uptake of chloromercuribenzene-p-sulphonic acid (CMBS) were studied in microdissected pancreatic islets of non-inbred ob/ob-mice. Na2SO4 stimulated the total islet cell uptake of CMBS but decreased the amount of CMBS remaining in islets after brief washing with L-cysteine. CaCl2 stimulated both the total and the cysteine-non-displaceable uptake; the stimulatory effect of CaCl2 on the cysteine-non-displaceable CMBS uptake was counteracted by Na2SO4. NaCl, KCl or choline chloride had no significant effect on the total islet cell uptake of CMBS, whereas LiCl was stimulatory. It is concluded that β-cells resemble erythrocytes in having a permeation path for CMBS that is inhibited by SO42−. By analogy with existing models of the erythrocyte membrane, it is suggested that the SO42−-sensitive path leads to sulphydryl groups controlling monovalent cationic permeability in β-cells.

GLUCOSE INHIBITION OF THE PERMEATION OF CHLOROMERCURIBENZENE-P-SULPHONIC ACID IN THE PLASMA MEMBRANE OF PANCREATIC β-CELLS

1975 ◽  
Vol 79 (1) ◽  
pp. 86-94 ◽  
Author(s):  
Monica Söderberg
Keyword(s):  
Plasma Membrane ◽  
Pancreatic Islets ◽  
Sulphonic Acid ◽  
Thiol Groups ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Glucose Inhibition ◽  
Microdissected Pancreatic Islets ◽  
Initial Binding ◽  
Glucose Analogue

ABSTRACT The transport of chloromercuribenzene-p-sulphonic acid (CMBS) was studied in microdissected pancreatic islets of ob/ob mice incubated in Krebs-Ringer bicarbonate medium. Glucose inhibited the islet uptake of CMBS. The initial binding of CMBS to superficial thiol groups was inhibited to a lesser extent than was its further permeation into the interior of the plasma membrane. The non-metabolized glucose analogue 3-0-methyl glucose had no effect on the permeation of CMBS. Whereas mannoheptulose, epinephrine and diazoxide lacked any effect in themselves, they tended to counteract the glucose inhibition of CMBS permeation. The ability of glucose to inhibit CMBS permeation is related to its insulin-releasing action rather than to its membrane transport or further metabolism.

scholarly journals Apolipoprotein CIII Reduces Proinflammatory Cytokine-Induced Apoptosis in Rat Pancreatic Islets via the Akt Prosurvival Pathway

Endocrinology ◽  
2011 ◽  
Vol 152 (8) ◽  
pp. 3040-3048 ◽  
Author(s):  
Joachim Størling ◽  
Lisa Juntti-Berggren ◽  
Gunilla Olivecrona ◽  
Michala C. Prause ◽  
Per-Olof Berggren ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Proinflammatory Cytokines ◽  
Islet Cell ◽  
Cell Function ◽  
No Production ◽  
Β Cells ◽  
Pancreatic Islet Cell ◽  
Rat Pancreatic Islets ◽  
Apolipoprotein Ciii ◽  
Induced Apoptosis

Apolipoprotein CIII (ApoCIII) is mainly synthesized in the liver and is important for triglyceride metabolism. The plasma concentration of ApoCIII is elevated in patients with type 1 diabetes (T1D), and in vitro ApoCIII causes apoptosis in pancreatic β-cells in the absence of inflammatory stress. Here, we investigated the effects of ApoCIII on function, signaling, and viability in intact rat pancreatic islets exposed to proinflammatory cytokines to model the intraislet inflammatory milieu in T1D. In contrast to earlier observations in mouse β-cells, exposure of rat islets to ApoCIII alone (50 μg/ml) did not cause apoptosis. In the presence of the islet-cytotoxic cytokines IL-1β + interferon-γ, ApoCIII reduced cytokine-mediated islet cell death and impairment of β-cell function. ApoCIII had no effects on mitogen-activated protein kinases (c-Jun N-terminal kinase, p38, and ERK) and had no impact on IL-1β-induced c-Jun N-terminal kinase activation. However, ApoCIII augmented cytokine-mediated nitric oxide (NO) production and inducible NO synthase expression. Further, ApoCIII caused degradation of the nuclear factor κB-inhibitor inhibitor of κB and stimulated Ser473-phosphorylation of the survival serine-threonine kinase Akt. Inhibition of the Akt signaling pathway by the phosphatidylinositol 3 kinase inhibitor LY294002 counteracted the antiapoptotic effect of ApoCIII on cytokine-induced apoptosis. We conclude that ApoCIII in the presence of T1D-relevant proinflammatory cytokines reduces rat pancreatic islet cell apoptosis via Akt.

scholarly journals Unraveling the role of the ghrelin gene peptides in the endocrine pancreas

2010 ◽  
Vol 45 (3) ◽  
pp. 107-118 ◽  
Author(s):  
Riccarda Granata ◽  
Alessandra Baragli ◽  
Fabio Settanni ◽  
Francesca Scarlatti ◽  
Ezio Ghigo
Keyword(s):  
Pancreatic Islets ◽  
Cell Biology ◽  
Islet Cell ◽  
Endocrine Pancreas ◽  
Islet Cells ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Islet Cell ◽  
Ghrelin Gene

The ghrelin gene peptides include acylated ghrelin (AG), unacylated ghrelin (UAG), and obestatin (Ob). AG, mainly produced by the stomach, exerts its central and peripheral effects through the GH secretagogue receptor type 1a (GHS-R1a). UAG, although devoid of GHS-R1a-binding affinity, is an active peptide, sharing with AG many effects through an unknown receptor. Ob was discovered as the G-protein-coupled receptor 39 (GPR39) ligand; however, its physiological actions remain unclear. The endocrine pancreas is necessary for glucose homeostasis maintenance. AG, UAG, and Ob are expressed in both human and rodent pancreatic islets from fetal to adult life, and the pancreas is the major source of ghrelin in the perinatal period. GHS-R1a and GPR39 expression has been shown in β-cells and islets, as well as specific binding sites for AG, UAG, and Ob. Ghrelin colocalizes with glucagon in α-islet cells, but is also uniquely expressed in ε-islet cells, suggesting a role in islet function and development. Indeed, AG, UAG, and Ob regulate insulin secretion in β-cells and isolated islets, promote β-cell proliferation and survival, inhibit β-cell and human islet cell apoptosis, and modulate the expression of genes that are essential in pancreatic islet cell biology. They even induce β-cell regeneration and prevent diabetes in streptozotocin-treated neonatal rats. The receptor(s) mediating their effects are not fully characterized, and a signaling crosstalk has been suggested. The present review summarizes the newest findings on AG, UAG, and Ob expression in pancreatic islets and the role of these peptides on β-cell development, survival, and function.

scholarly journals Effects of glucose and other modifiers of insulin release on the oxidative metabolism of amino acids in micro-dissected pancreatic islets

1971 ◽  
Vol 123 (4) ◽  
pp. 513-521 ◽  
Author(s):  
B. Hellman ◽  
J. Sehlin ◽  
I.-B. Täljedal
Keyword(s):  
Amino Acids ◽  
Glucose Metabolism ◽  
Cyclic Amp ◽  
Pancreatic Islets ◽  
Insulin Release ◽  
Β Cells ◽  
Insulin Secretagogues ◽  
Concentration Changes ◽  
Microdissected Pancreatic Islets ◽  
Oxidation Of Glucose

The oxidation of alanine, arginine, leucine, glucose, and pyruvate was studied in microdissected pancreatic islets of obese–hyperglycaemic mice. The following main observations were made. The oxidation of glucose was enhanced severalfold when its concentration was raised from 3 to 20mm. At the latter concentration the rate was about 65mmol/h per kg dry wt. The oxidation of 17mm-pyruvate amounted to 20mmol/h per kg dry wt. indicating a significant entry of this compound into the β-cells. Leucine oxidation was little affected by concentration changes above 5mm, the rate at 20mm corresponding to about 25% of that obtained with 20mm-glucose. In the absence of glucose, the oxidation of alanine or arginine was barely significant. Glucose stimulated the oxidation of alanine but depressed that of leucine. These effects of glucose were blocked by mannoheptulose or iodoacetamide but were not influenced by adrenaline, diazoxide, dibutyryl 3′:5′-cyclic AMP, or glibenclamide. The rate of alanine oxidation was doubled in the presence of 17mm-pyruvate but was unaffected by citrate or succinate. Succinate depressed the oxidation of leucine. Neither alanine nor leucine significantly affected the oxidation of glucose. It is suggested that the effects of glucose on the oxidation of alanine and leucine were mediated by metabolism of the sugar, and that amino acids do not act as insulin secretagogues by serving as fuels for the β-cells. The results are consistent with the existence of mechanisms auxiliary to glucose metabolism for control of insulin release.

scholarly journals Immunohistochemistry of Pancreatic Islet Cell Tumors in the Ferret (Mustela putorius furo)

1997 ◽  
Vol 34 (5) ◽  
pp. 387-393 ◽  
Author(s):  
G. A. Andrews ◽  
N. C. Myers ◽  
C. Chard-Bergstrom
Keyword(s):  
Pancreatic Islets ◽  
Pancreatic Islet ◽  
Pancreatic Polypeptide ◽  
Islet Cell ◽  
Islet Cells ◽  
Neuron Specific Enolase ◽  
Islet Cell Tumors ◽  
Pancreatic Islet Cell ◽  
Formalin Fixed Paraffin Embedded ◽  
Pancreatic Islet Cell Tumors

Twenty-two pancreatic islet cell tumors and normal pancreatic islets from ferrets were evaluated by immunohistochemistry for expression of the peptide hormones insulin, somatostatin, glucagon, and pancreatic polypeptide (PP) and the neuroendocrine markers chromogranin A (CgA) and neuron-specific enolase (NSE). In normal pancreatic islets, the majority of cells stained strongly with CgA and NSE. A cells, B cells, D cells, and PP cells stained strongly with glucagon, insulin, somatostatin, and PP, respectively. All 22 tumors stained with CgA and NSE. The proportion of cells within tumors staining for CgA was variable, but more than half of the cells stained positively in 18 of the tumors. The intensity of staining for CgA was strong (reactivity equivalent to or greater than normal islet cells in adjacent tissue) in 11 moderate in six, and weak in five of the tumors. All tumors stained for NSE, with ≥50% of the cells staining in 21 of the tumors, and the intensity of staining was strong in 18 of the tumors. Twenty of 22 tumors stained positively for insulin, with ≥50% of the cells staining in 19 of them. The intensity of staining for insulin was strong in 12, moderate in seven, and weak in one of the tumors. Approximately ≤1% of the cells in 15 of 22 tumors stained for somatostatin, five tumors stained for pancreatic polypeptide, and three tumors stained for glucagon. These data indicate that the majority of islet cell tumors of ferrets express immunohistochemically detectable insulin. CgA and NSE are both useful general markers for such tumors, including those that are insulin negative. Commercially available antisera to CgA, NSE, insulin, glucagon, somatostatin, and PP work well in formalin-fixed, paraffin-embedded tissue for immunophenotyping islet cell tumors in the ferret.

scholarly journals Glucose-dependent blood flow dynamics in murine pancreatic islets in vivo

2010 ◽  
Vol 298 (4) ◽  
pp. E807-E814 ◽  
Author(s):  
Lara R. Nyman ◽  
Eric Ford ◽  
Alvin C. Powers ◽  
David W. Piston
Keyword(s):  
Blood Flow ◽  
Blood Glucose ◽  
Pancreatic Islets ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Cell Types ◽  
Β Cells ◽  
Islet Blood Flow ◽  
Significant Difference

Pancreatic islets are highly vascularized and arranged so that regions containing β-cells are distinct from those containing other cell types. Although islet blood flow has been studied extensively, little is known about the dynamics of islet blood flow during hypoglycemia or hyperglycemia. To investigate changes in islet blood flow as a function of blood glucose level, we clamped blood glucose sequentially at hyperglycemic (∼300 mg/dl or 16.8 mM) and hypoglycemic (∼50 mg/dl or 2.8 mM) levels while simultaneously imaging intraislet blood flow in mouse models that express green fluorescent protein in the β-cells or yellow fluorescent protein in the α-cells. Using line scanning confocal microscopy, in vivo blood flow was assayed after intravenous injection of fluorescent dextran or sulforhodamine-labeled red blood cells. Regardless of the sequence of hypoglycemia and hyperglycemia, islet blood flow is faster during hyperglycemia, and apparent blood volume is greater during hyperglycemia than during hypoglycemia. However, there is no change in the order of perfusion of different islet endocrine cell types in hypoglycemia compared with hyperglycemia, with the islet core of β-cells usually perfused first. In contrast to the results in islets, there was no significant difference in flow rate in the exocrine pancreas during hyperglycemia compared with hypoglycemia. These results indicate that glucose differentially regulates blood flow in the pancreatic islet vasculature independently of blood flow in the rest of the pancreas.

Islet Cell Transplantation: In Vivo and in Vitro Functional Assessment of Nonhuman Primate Pancreatic Islets

2000 ◽  
Vol 9 (3) ◽  
pp. 409-414 ◽  
Author(s):  
Alessandra Rammcoli ◽  
Nicola Cautero ◽  
Camillo Ricordi ◽  
Michele Masetti ◽  
Ruth D. Molano ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Cell Transplantation ◽  
Functional Assessment ◽  
Nonhuman Primate ◽  
Islet Cell ◽  
Islet Cell Transplantation

scholarly journals Regulation of glucokinase in pancreatic islets by prolactin: a mechanism for increasing glucose-stimulated insulin secretion during pregnancy

2007 ◽  
Vol 193 (3) ◽  
pp. 367-381 ◽  
Author(s):  
Anthony J Weinhaus ◽  
Laurence E Stout ◽  
Nicholas V Bhagroo ◽  
T Clark Brelje ◽  
Robert L Sorenson
Keyword(s):  
Insulin Secretion ◽  
Glucose Metabolism ◽  
Pancreatic Islets ◽  
Glucose Transporter ◽  
Β Cells ◽  
Glucose Transporter 2 ◽  
Underlying Mechanisms ◽  
Glucose Stimulated Insulin Secretion ◽  
Induced Changes

Glucokinase activity is increased in pancreatic islets during pregnancy and in vitro by prolactin (PRL). The underlying mechanisms that lead to increased glucokinase have not been resolved. Since glucose itself regulates glucokinase activity in β-cells, it was unclear whether the lactogen effects are direct or occur through changes in glucose metabolism. To clarify the roles of glucose metabolism in this process, we examined the interactions between glucose and PRL on glucose metabolism, insulin secretion, and glucokinase expression in insulin 1 (INS-1) cells and rat islets. Although the PRL-induced changes were more pronounced after culture at higher glucose concentrations, an increase in glucose metabolism, insulin secretion, and glucokinase expression occurred even in the absence of glucose. The presence of comparable levels of insulin secretion at similar rates of glucose metabolism from both control and PRL-treated INS-1 cells suggests the PRL-induced increase in glucose metabolism is responsible for the increase in insulin secretion. Similarly, increases in other known PRL responsive genes (e.g. the PRL receptor, glucose transporter-2, and insulin) were also detected after culture without glucose. We show that the upstream glucokinase promoter contains multiple STAT5 binding sequences with increased binding in response to PRL. Corresponding increases in glucokinase mRNA and protein synthesis were also detected. This suggests the PRL-induced increase in glucokinase mRNA and its translation are sufficient to account for the elevated glucokinase activity in β-cells with lactogens. Importantly, the increase in islet glucokinase observed with PRL is in line with that observed in islets during pregnancy.

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