The inhibition of stimulus-secretion coupling in pancreatic islets by volatile anaesthetics does not involve pertussis toxin sensitive G-proteins

1994 ◽  
Vol 22 (2) ◽  
pp. 133S-133S ◽  
Author(s):  
JOAN P. DESBOROUGH ◽  
PETER M. JONES ◽  
SHANTA J. PERSAUD ◽  
SIMON L. HOWELL
Keyword(s):  
Pancreatic Islets ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Volatile Anaesthetics ◽  
Stimulus Secretion Coupling

FUNCTIONAL INTERACTIONS OF PERTUSSIS TOXIN-SENSITIVE G-PROTEINS WITH THE TRANSFECTED μ-OPIOID RECEPTOR IN RAT 1 FIBROBLASTS

Analgesia ◽  
1995 ◽  
Vol 1 (4) ◽  
pp. 438-441
Author(s):  
Zafiroula Georgoussi ◽  
Ian Mullaney ◽  
Alan Wise ◽  
Craig Carr ◽  
Graeme Milligan
Keyword(s):  
G Proteins ◽  
Opioid Receptor ◽  
Pertussis Toxin ◽  
Functional Interactions ◽  
Μ Opioid Receptor

scholarly journals Erratum

1991 ◽  
Vol 11 (4) ◽  
pp. 706-706
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Equilibrium State ◽  
Rat Brain ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Adp Ribosylation ◽  
Gtp Binding ◽  
Reconstituted System ◽  
Α Subunits

Ischemia of Rat Brain Decreases Pertussis Toxin-Catalyzed [32P] ADP Ribosylation of GTP-Binding Proteins (Gi1 and G0) in Membranes Katsunobu Takenaka, Yasunori Kanaho, Koh-ichi Nagata, Noboru Sakai, Hiromu Yamada, Yoshinori Nozawa [ Originally published in Journal of Cerebral Blood Flow and Metabolism 1991;11:155–160] On page 158 of the above, arrows were erroneously deleted from the equation in the following passage: Heterotrimers of G proteins that bind GDP to α subunits seem to be the preferred substrates for PTcatalyzed ADP ribosylation since guanine nucleotides (GDP and GTP) and 13'Y subunits stimulate ADP ribosylation in the reconstituted system and in membranes (Tsai et aI., 1984). These results indicate that the G proteins may exist at the equilibrium state as shown below: This omission was the result of a typesetting error, which the publisher regrets.

scholarly journals Critical Role of Pertussis Toxin Sensitive G Proteins in the Activation of TRPC4 and TRPC5 Channels

2010 ◽  
Vol 98 (3) ◽  
pp. 326a-327a
Author(s):  
Rui Xiao ◽  
Jinbin Tian ◽  
Jisen Tang ◽  
Alexander V. Zholos ◽  
Michael X. Zhu
Keyword(s):  
G Proteins ◽  
Pertussis Toxin ◽  
Critical Role ◽  
Trpc5 Channels

scholarly journals The possible mechanisms by which phanoside stimulates insulin secretion from rat islets

2007 ◽  
Vol 192 (2) ◽  
pp. 389-394 ◽  
Author(s):  
Nguyen Khanh Hoa ◽  
Åke Norberg ◽  
Rannar Sillard ◽  
Dao Van Phan ◽  
Nguyen Duy Thuan ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
B Cells ◽  
Pancreatic Islets ◽  
Insulin Release ◽  
Pertussis Toxin ◽  
Insulin Response ◽  
Gk Rat ◽  
Isolated Pancreatic Islets ◽  
Gk Rats ◽  
Rat Islets

We recently showed that phanoside, a gypenoside isolated from the plant Gynostemma pentaphyllum, stimulates insulin secretion from rat pancreatic islets. To study the mechanisms by which phanoside stimulates insulin secretion. Isolated pancreatic islets of normal Wistar (W) rats and spontaneously diabetic Goto-Kakizaki (GK) rats were batch incubated or perifused. At both 3.3 and 16.7 mM glucose, phanoside stimulated insulin secretion several fold in both W and diabetic GK rat islets. In perifusion of W islets, phanoside (75 and 150 μM) dose dependently increased insulin secretion that returned to basal levels when phanoside was omitted. When W rat islets were incubated at 3.3 mM glucose with 150 μM phanoside and 0.25 mM diazoxide to keep K-ATP channels open, insulin secretion was similar to that in islets incubated in 150 μM phanoside alone. At 16.7 mM glucose, phanoside-stimulated insulin secretion was reduced in the presence of 0.25 mM diazoxide (P<0.01). In W islets depolarized by 50 mM KCl and with diazoxide, phanoside stimulated insulin release twofold at 3.3 mM glucose but did not further increase the release at 16.7 mM glucose. When using nimodipine to block L-type Ca2+ channels in B-cells, phanoside-induced insulin secretion was unaffected at 3.3 mM glucose but decreased at 16.7 mM glucose (P<0.01). Pretreatment of islets with pertussis toxin to inhibit exocytotic Ge-protein did not affect insulin response to 150 μM phanoside. Phanoside stimulated insulin secretion from Wand GK rat islets. This effect seems to be exerted distal to K-ATP channels and L-type Ca2+ channels, which is on the exocytotic machinery of the B-cells.

Immunological characterization of the guanine-nucleotide binding proteins Gi and Go in rat islets of Langerhans

1992 ◽  
Vol 8 (2) ◽  
pp. 103-108 ◽  
Author(s):  
N. S. Berrow ◽  
G. Milligan ◽  
N. G. Morgan
Keyword(s):  
G Proteins ◽  
Islets Of Langerhans ◽  
Pertussis Toxin ◽  
Nucleotide Binding ◽  
Molecular Forms ◽  
Antigenic Determinants ◽  
Guanine Nucleotide ◽  
Rat Islets ◽  
Guanine Nucleotide Binding ◽  
Rat Islets Of Langerhans

ABSTRACT Inhibition of insulin secretion from rat islets of Langerhans is known to involve at least one pertussis toxin-sensitive guanine-nucleotide binding (G) protein. We have used antisera raised against unique antigenic determinants of different members of the family of pertussis toxin-sensitive G proteins to identify these proteins in rat islets. Antiserum SG1, which recognizes both Gi1 and Gi2, reacted with an islet protein having an approximate Mr of 40 000. Antiserum IlC (Gi1 specific) failed to recognize any islet proteins, suggesting that Gi2 is present in much greater amounts than Gi1. Indeed, Gi1 levels were below the detection limit of a sensitive immunogold/silver-staining method, indicating that it may be absent from the cells of rat islets. Two different antisera were used to identify Go-like G proteins in rat islet homogenates. Both antisera reacted with a protein band which, under appropriate conditions, could be resolved to reveal two separate proteins of Mr 39–40 000. Thus, at least two molecular forms of Go are present in rat islets. Subcellular fractionation indicated that all three G proteins identified in this study (Gi2 and two forms of Go) are localized to islet membranes. No immunoreactivity could be detected in the cytosolic fraction.

scholarly journals Arachidonic acid release from rat Leydig cells: the involvement of G protein, phospholipase A2 and regulation of cAMP production

2002 ◽  
Vol 172 (1) ◽  
pp. 95-104 ◽  
Author(s):  
AM Ronco ◽  
PF Moraga ◽  
MN Llanos
Keyword(s):  
Arachidonic Acid ◽  
Fatty Acid ◽  
G Protein ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Leydig Cells ◽  
Inhibitory Effect ◽  
Receptor Interaction ◽  
Dependent Manner ◽  
Camp Production

We have previously demonstrated that the release of arachidonic acid (AA) from human chorionic gonadotropin (hCG)-stimulated Leydig cells occurs in a dose- and time-dependent manner. In addition, the amount of AA released was dependent on the hormone-receptor interaction and the concentration of LH-hCG binding sites on the cell surface. The present study was conducted to evaluate the involvement of phospholipase A(2) (PLA(2)) and G proteins in AA release from hormonally stimulated rat Leydig cells, and the possible role of this fatty acid in cAMP production. Cells were first prelabelled with [(14)C]AA to incorporate the fatty acid into cell phospholipids, and then treated in different ways to evaluate AA release. hCG (25 mIU) increased the release of AA to 180+/-12% when compared with AA released from control cells, arbitrarily set as 100%. Mepacrine and parabromophenacyl bromide (pBpB), two PLA(2) inhibitors, decreased the hormone-stimulated AA release to 85+/-9 and 70+/-24% respectively. Conversely, melittin, a PLA(2) stimulator, increased the release of AA up to 200% over control. The inhibitory effect of mepacrine on the release of AA was evident in hCG-treated Leydig cells, but not in the melittin-treated cells. To determine if the release of AA was also mediated through a G protein, cells were first permeabilized and subsequently treated with pertussis toxin or GTPgammaS, a non-hydrolyzable analog of GTP. Results demonstrate that GTPgammaS was able to induce a similar level of the release of AA as hCG. In addition, pertussis toxin completely abolished the stimulatory effect of hCG on the release of AA, indicating that a member of the G(i) family was involved in the hCG-dependent release of AA. Cells treated with PLA(2) inhibitors did not modify cAMP production, but exogenously added AA significantly reduced cAMP production from hCG-treated Leydig cells, in a manner dependent on the concentration of AA and hCG. Results presented here suggest an involvement of PLA(2) and G proteins in the release of AA from hCG-stimulated Leydig cells, and under particular conditions, regulation of cAMP production by this fatty acid in these cells.

Nitric oxide donor SIN-1 inhibits insulin release

1996 ◽  
Vol 271 (4) ◽  
pp. C1098-C1102 ◽  
Author(s):  
A. Sjoholm
Keyword(s):  
Nitric Oxide ◽  
Diabetes Mellitus ◽  
Protein Kinase C ◽  
Insulin Secretion ◽  
Protein Kinase ◽  
Beta Cell ◽  
Pancreatic Islets ◽  
Insulin Release ◽  
Kinase C ◽  
Stimulus Secretion Coupling

Preceding the onset of insulin-dependent diabetes mellitus, pancreatic islets are infiltrated by macrophages secreting interleukin-1 beta, which exerts cytotoxic and inhibitory actions on islet beta-cell insulin secretion through induction of nitric oxide (NO) synthesis. The influence of the NO donor 3-morpholinosydnonimine (SIN-1) on insulin secretion from isolated pancreatic islets in response to various secretagogues was investigated. Stimulation of insulin release evoked by glucose, phospholipase C activation with carbachol, and protein kinase C activation with phorbol ester were obtained by SIN-1, whereas the response to adenylyl cyclase activation or K(+)-induced depolarization was not affected. It is concluded that enzymes involved in glucose catabolism, phospholipase C or protein kinase C, may be targeted by NO. Reversal of SIN-1 inhibition of glucose-stimulated insulin release by dithiothreitol suggests that NO may inhibit insulin secretion partly by S-nitrosylation of thiol residues in key proteins in the stimulus-secretion coupling. These adverse effects of NO on the beta-cell stimulus-secretion coupling may be of importance for the development of the impaired insulin secretion characterizing diabetes mellitus.

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