scholarly journals Pertussis toxin abolishes the inhibitory effects of prostaglandins E1, E2,I2 and F2alpha on hormone-induced cAMP accumulation in cultured hepatocytes

1988 ◽  
Vol 172 (2) ◽  
pp. 293-297 ◽  
Author(s):  
Oyvind MELIEN ◽  
Randi WINSNES ◽  
Magne REFSNES ◽  
Ivar P. GLADHAUG ◽  
Thoralf CHRISTOFFERSEN
Keyword(s):  
Pertussis Toxin ◽  
Camp Accumulation ◽  
Cultured Hepatocytes ◽  
Inhibitory Effects

Somatostatin receptors on canine fundic D-cells: evidence for autocrine regulation of gastric somatostatin

1989 ◽  
Vol 257 (2) ◽  
pp. G235-G241
Author(s):  
J. Park ◽  
T. Chiba ◽  
K. Yokotani ◽  
J. DelValle ◽  
T. Yamada
Keyword(s):  
Pertussis Toxin ◽  
Binding Sites ◽  
Dissociation Constants ◽  
Somatostatin Receptors ◽  
Biologically Active ◽  
Camp Accumulation ◽  
Gut Peptides ◽  
Inhibitory Effects ◽  
D Cells

Somatostatin is known to have inhibitory effects on the release and action of a wide variety of gut peptides. Previous studies in vivo have suggested a potential inhibitory role for somatostatin even on its own secretion. To determine whether this autoregulatory effect is the result of a direct action of the peptide on the cell that is responsible for its secretion, we examined the effect of a non-immunoreactive but biologically active analogue of somatostatin ([Leu8-D-Trp22-Tyr25]S28) on release of somatostatin-like immunoreactivity (SLI) from isolated canine fundic D-cells. We identified somatostatin binding sites with dissociation constants of 1.2 X 10(-9) and 3.8 X 10(-8) M that coenriched with D-cells. Somatostatin 14, somatostatin 28, and [Leu8-D-Trp22-Tyr25]S28 were equivalent in displacing 125I-[Leu8-D-Trp22-Tyr25]S28 from the binding sites. [Leu8-D-Trp22-Tyr25]S28 inhibited SLI release from D-cells stimulated with (DBcAMP), and pentagastrin. Pertussis toxin pretreatment prevented the inhibitory effects of [Leu8-D-Trp22-Tyr25]S28 on both SLI secretion and cAMP accumulation by on both SLI secretion and cAMP accumulation by D-cells stimulated with epinephrine and forskolin. In contrast, [Leu8-D-Trp22-Tyr25]S28 inhibition of SLI release induced by DBcAMP and pentagastrin was not altered by pertussis toxin. Our data suggest that somatostatin autoregulates its own secretion via specific receptors on D-cells. This inhibitory effect is mediated by mechanisms that are both dependent on and independent of pertussis toxin-sensitive inhibitory guanine nucleotide binding proteins.

Interaction of adenosine with vasopressin in the inner medullary collecting duct

1990 ◽  
Vol 259 (4) ◽  
pp. F679-F687 ◽  
Author(s):  
Y. Yagil
Keyword(s):  
Pertussis Toxin ◽  
Receptor Agonist ◽  
Collecting Duct ◽  
Phosphodiesterase Inhibitor ◽  
Inhibitory Effects ◽  
Inner Medullary Collecting Duct ◽  
Medullary Collecting Duct ◽  
Camp Levels ◽  
Dose Dependent ◽  
Stimulation Of

Administration of adenosine (Ado) into rat renal artery induces dose-dependent diuresis that is independent of changes in glomerular filtration rate or renal blood flow, suggesting a direct effect on tubule H2O reabsorption. To test the hypothesis that Ado modulates cellular action of arginine vasopressin (AVP) as a tubular mechanism for the diuretic effect of Ado, interaction of Ado with AVP was studied in primary cell culture of rat inner medullary collecting duct (IMCD) epithelium. Stimulation of cells with 10(-6) M AVP in presence of 0.1 mM Ro 20-1724, a nonmethylxanthine phosphodiesterase inhibitor that has no effect on Ado receptors, increased adenosine 3',5'-cyclic monophosphate (cAMP) levels twofold or more above baseline. Stimulation of cells with the A1 Ado-receptor agonist N6-cyclohexyladenosine (CHA), the A2-receptor agonist 5'-(N-ethylcarboxamido)-adenosine (NECA), or with the P-site agonist 2',5'-dideoxyadenosine (DDA) significantly inhibited the AVP-stimulated cAMP response. Preincubation with pertussis toxin abolished the inhibitory effects of CHA and NECA, but not of DDA. The data suggest that, in the rat IMCD, Ado modulates AVP action by interfering with its ability to stimulate formation of its second messenger, cAMP. This effect is mediated by the extracellular Ado receptors A1 and A2 and by the intracellular P-site. It occurs by at least two pathways, one sensitive and the other insensitive to pertussis toxin.

Changes in expression of a functional Gi protein in cultured rat heart cells

1988 ◽  
Vol 255 (1) ◽  
pp. C51-C59 ◽  
Author(s):  
I. S. Allen ◽  
S. T. Gaa ◽  
T. B. Rogers
Keyword(s):  
Adenylate Cyclase ◽  
Pertussis Toxin ◽  
Rat Heart ◽  
Neonatal Rat ◽  
Heart Cells ◽  
Dependent Manner ◽  
Camp Accumulation ◽  
Ang Ii ◽  
Rat Heart Myocytes ◽  
Neonatal Rat Heart

The muscarinic cholinergic agonist, carbachol, and pertussis toxin were used to examine the functional status of the guanine nucleotide-binding protein that inhibits adenylate cyclase (Gi) in cultured neonatal rat heart myocytes. The isoproterenol stimulation of adenylate cyclase activity in myocyte membranes and adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in intact cells (4 days in culture) were insensitive to carbachol (0.1 mM). However, in cells cultured for 11 days, carbachol (0.1 mM) inhibited isoproterenol-stimulated cAMP accumulation by 30%. Angiotensin II (ANG II) was also found to inhibit isoproterenol-stimulated cAMP accumulation in day 11 cells in a dose-dependent manner. Pertussis toxin treatment reversed the inhibitory effects of both ANG II and carbachol, suggesting a role for Gi in the process. Carbachol binding to membranes from day 4 cells was relatively insensitive to guanine nucleotides when compared with binding to membranes from day 11 or adult cells. Furthermore, pertussis toxin-mediated 32P incorporation into a 39- to 41-kDa substrate in day 11 membranes was increased 3.2-fold over that measured in day 4 membranes. These findings support the view that, although Gi is expressed, it is nonfunctional in 4-day-old cultured neonatal rat heart myocytes and acquisition of functional Gi is dependent on culture conditions. Furthermore, the ANG II receptor can couple to Gi in heart.

Do β2-adrenergic receptors modulate Ca2+ in adult rat ventricular myocytes?

1998 ◽  
Vol 274 (4) ◽  
pp. H1308-H1314 ◽  
Author(s):  
Michael A. Laflamme ◽  
Peter L. Becker
Keyword(s):  
Pertussis Toxin ◽  
Calcium Homeostasis ◽  
Adrenergic Receptors ◽  
Calcium Current ◽  
Ventricular Myocytes ◽  
Camp Accumulation ◽  
Camp Production ◽  
Rat Ventricular Myocytes ◽  
Adult Rat

We examined the role of β2-adrenergic receptors (ARs) in modulating calcium homeostasis in rat ventricular myocytes. Zinterol (10 μM), an agonist with a 25-fold greater affinity for β2-ARs over β1-ARs, modestly enhanced L-type calcium current ( I Ca) magnitude by ∼30% and modestly accelerated the rate of Ca2+ concentration ([Ca2+]) decline (∼35%) but had little effect on the magnitude of the [Ca2+] transient (a nonsignificant 6% increase). However, 1 μM of the highly selective β1-AR antagonist CGP-20712A completely blocked the I Ca increase induced by 10 μM zinterol. Pretreatment of cells with pertussis toxin (PTX) did not alter I Ca enhancement by 10 μM zinterol, although it did abolish the ability of acetylcholine to block the forskolin-induced enhancement of I Ca. Zinterol (10 μM) approximately doubled adenosine 3′,5′-cyclic monophosphate (cAMP) accumulation, although one-half of this increase was blocked by CGP-20712A. In contrast, 1 μM of the nonselective β-agonist isoproterenol increased cAMP production 15-fold. Thus we found no evidence that activation of β2-ARs modulates calcium homeostasis in rat ventricular myocytes, even after treatment with PTX.

Na+-K+-ATPase-G protein coupling in myocardial sarcolemma: separation and reconstitution

1991 ◽  
Vol 261 (4) ◽  
pp. L87-L91
Author(s):  
Mikhail P. Danilenko ◽  
Vera C. Turmukhambetova ◽  
Oleg V. Yesirev ◽  
Vsevolod A. Tkachuk ◽  
Mikhail P. Panchenko
Keyword(s):  
Atpase Activity ◽  
Pertussis Toxin ◽  
Inhibitory Concentration ◽  
Gel Filtration ◽  
Protein S ◽  
Half Maximum ◽  
Inhibitory Effects ◽  
Cardiac Sarcolemma ◽  
Dependent Inhibition ◽  
Zwitterionic Detergent

The cholinergic agonist carbachol produces a concentration-dependent (half-maximum inhibitory concentration = 0.9 μM) decrease in the Na+-K+-adenosine triphosphatase (ATPase) activity of rabbit cardiac sarcolemma that occurred only in the presence of guanosine 5'-[ggr-thio]triphosphate (0.1 μM GTPggrS) and reached 40% inhibition. The inhibition is blocked by the muscarinic receptor antagonist atropine (10 μM) and is abolished in sarcolemma treated with pertussis toxin (20 μg/ml) in the presence of 100 μM NAD. GTPggrS alone reduces Na+-K+-ATPase activity by 45% (half-maximum inhibitory = 1 μM). The apparent affinity of the enzyme for GTPgγS is increased ≈10-fold in the presence of 1 μM carbachol. In sarcolemma solubilized with the zwitterionic detergent 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS, 10 mM), the GTPgγS-dependent inhibition of the Na+-K+-ATPase is also observed. Gel filtration of a CHAPS extract of sarcolemma on a Sepharose CL-6B column resulted in a separation of Na+-K+-ATPase and pertussis toxin-sensitive Gi activities. Na+-K+-ATPase activity that was separated on the column lost its sensitivity to the inhibitory action of guanine nucleotides. Inhibitory effects (20–30%) of guanosine 5'-triphosphate analogues [Gpp(NH)p, GTPggrS, or Gpp(CH2)p] at micromolar concentrations were restored when the Na+-K+-ATPase activity was recombined with fractions that contained the pertussis toxin-sensitive Gi protein(s). Similar concentrations of guanosine 5'-triphosphate, guanosine 5'-diphosphate, guanosine-5' -[beta-thio]diphosphate, or App(NH)p were unable to induce the Gi protein-mediated attenuation of Na+-K+-ATPase activity in the reconstitution system. These results suggest that a pertussis toxin-sensitive Gi protein may act as a transducer of the inhibitory hormonal signals on Na+-K+-ATPase in the sarcolemma. cardiac sarcolemma

scholarly journals Inhibitory Effects of Glibenclamide and Pertussis Toxin on the Attenuation of lschemia-Induced Myocardial Acidosis Following lschemic Preconditioning in Dogs

1997 ◽  
Vol 61 (8) ◽  
pp. 709-714 ◽  
Author(s):  
Kazuhiko Miura ◽  
Seiichiro Kano ◽  
Tohru Nakai ◽  
Kumi Satoh ◽  
Katsuji Hoshi ◽  
...  
Keyword(s):  
Pertussis Toxin ◽  
Inhibitory Effects

scholarly journals Interleukin 1β and tumour necrosis factor α inhibit acid secretion in cultured rabbit parietal cells by multiple pathways

Gut ◽  
1998 ◽  
Vol 42 (2) ◽  
pp. 227-234 ◽  
Author(s):  
I L P Beales ◽  
J Calam
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Pertussis Toxin ◽  
Tumour Necrosis ◽  
Parietal Cells ◽  
Tumour Necrosis Factor Α ◽  
Inhibitory Effects ◽  
Tnf Α ◽  
Factor Α ◽  
Necrosis Factor

Background—The cytokines interleukin 1β (IL-1β) and tumour necrosis factor α (TNF-α) are inhibitors of gastric acid secretion when administered systemically.Aims—To investigate the inhibitory effect of IL-1β and TNF-α on cultured, acid secreting parietal cells in order to determine the mechanism of this inhibition.Methods—Rabbit parietal cells were prepared by collagenase-EDTA digestion and counter flow elutriation. Acid secretory activity was assessed by aminopyrine accumulation.Results—IL-1β and TNF-α inhibited basal and stimulated acid secretion in a dose dependent manner; near maximal effects were seen with both at 10 ng/ml. Inhibition was maximal with 15 minutes pretreatment but seen with up to 18 hours of preincubation. Both cytokines inhibited histamine, carbachol, gastrin, forskolin, and A23187 stimulated acid secretion but had no effect on stimulation by dibutyryl-cAMP. Inhibition of acid secretion was not accompanied by a change in radioligand binding to histamine H2 or gastrin/CCKB receptors. Pertussis toxin abolished the inhibitory effects on histamine and forskolin stimulation. The tyrosine kinase inhibitor herbimycin reduced the inhibitory effects of TNF-α against all stimuli but only reduced the effects of IL-1β against histamine and forskolin stimulation.Conclusions—IL-1β and TNF-α seem to inhibit parietal cell acid secretion by multiple pathways; the inhibition occurs at postreceptor level and involves pertussis toxin and tyrosine kinase dependent and independent pathways. Mucosal production of cytokines may be important in the regulation of gastric acid secretion.

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