EFFECT OF PHENYLBUTAZONE ON BICARBONATE SECRETION IN THE EQUINE COLON IN VITRO

PKC has been shown to regulate epithelial Cl- secretion in a variety of models. However, the role of PKC in duodenal mucosal bicarbonate secretion is less clear. We aimed to investigate the role of PKC in regulation of duodenal mucosal bicarbonate secretion. Bicarbonate secretion by murine duodenal mucosa was examined in vitro in Ussing chambers using a pH-stat technique. PKC isoform expression and activity were assessed by Western blotting and in vitro kinase assays, respectively. PMA (an activator of PKC) alone had no effect on duodenal bicarbonate secretion or short-circuit current ( Isc). When PMA and dibutyryl-cAMP (db-cAMP) were added simultaneously, PMA failed to alter db-cAMP-stimulated duodenal bicarbonate secretion or Isc ( P > 0.05). However, a 1-h preincubation with PMA potentiated db-cAMP-stimulated duodenal bicarbonate secretion and Isc in a concentration-dependent manner (from 10-8 to 10-5M) ( P < 0.05). PMA preincubation had no effects on carbachol- or heat-stable toxin-stimulated bicarbonate secretion. Western blot analysis revealed that PKCα, -γ, -ϵ, -θ, -μ, and -ι/λ were expressed in murine duodenal mucosa. Ro 31–8220 (an inhibitor active against PKCϵ, -α, -β, and -γ), but not Gö 6983 (an inhibitor active against PKCα, -γ, -β, and -δ), reversed the potentiating effect of PMA on db-cAMP-stimulated bicarbonate secretion. PMA also time- and concentration-dependently increased the activity of PKCϵ, an effect that was prevented by Ro 31–8220 but not Gö 6983. These results demonstrate that activation of PKC potentiates cAMP-stimulated duodenal bicarbonate secretion, whereas it does not modify basal secretion. The effect of PKC on cAMP-stimulated bicarbonate secretion is mediated by the PKCϵ isoform.

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Fluid Movement Across the Wall of the Small Intestine in Vitro

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1956.187.2.244 ◽

1956 ◽

Vol 187 (2) ◽

pp. 244-246 ◽

Cited By ~ 14

Author(s):

T. Hastings Wilson

Keyword(s):

Small Intestine ◽

Sodium Chloride ◽

Saline Solution ◽

Isotonic Saline ◽

Bicarbonate Secretion ◽

Serosal Side ◽

Fluid Movement ◽

Mucosal Side

Small sacs of everted jejunum of the hamster were incubated in sugar free bicarbonate-saline solution in vitro. Both fluid and sodium chloride moved across the wall of the intestine from mucosal to serosal side. This movement of isotonic saline solution across the intestine was inhibited anaerobically. A small bicarbonate secretion was noted in the direction of serosal to mucosal side.

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Protease-activated receptor-2 regulates bicarbonate secretion by pancreatic duct cells in vitro

Surgery ◽

10.1016/j.surg.2004.01.018 ◽

2004 ◽

Vol 136 (3) ◽

pp. 669-676 ◽

Cited By ~ 10

Author(s):

Carlos Alvarez ◽

Joseph P. Regan ◽

Demetri Merianos ◽

Barbara L. Bass

Keyword(s):

Pancreatic Duct ◽

Bicarbonate Secretion ◽

Duct Cells ◽

Pancreatic Duct Cells ◽

Protease Activated Receptor 2

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Intestinal bicarbonate secretion in Amphiuma measured by pH stat in vitro: relationship with metabolism and transport of sodium and chloride ions.

The Journal of Physiology ◽

10.1113/jphysiol.1981.sp013717 ◽

1981 ◽

Vol 314 (1) ◽

pp. 429-443 ◽

Cited By ~ 14

Author(s):

M A Imon ◽

J F White

Keyword(s):

Chloride Ions ◽

Bicarbonate Secretion ◽

Ph Stat

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Bicarbonate secretion by rabbit proximal colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1986.251.4.g436 ◽

1986 ◽

Vol 251 (4) ◽

pp. G436-G445 ◽

Cited By ~ 5

Author(s):

S. K. Sullivan ◽

P. L. Smith

Keyword(s):

Transport Process ◽

Short Circuit ◽

Proximal Colon ◽

Bathing Solution ◽

Bicarbonate Secretion ◽

Rabbit Ileum ◽

Ussing Chambers ◽

Ph Stat ◽

Dependent Mechanism

Stripped segments of proximal colon (1-6 cm distal to the ampulla caecalis coli) were studied in vitro in Ussing chambers under short-circuit conditions using the pH-stat technique. With glucose and HCO3-CO2 present in the serosal bathing solution only, proximal colon alkalinizes the luminal bathing solution at a rate of 2.1 +/- 0.2 mu eq X h-1 X cm-2 (n = 36). With HCO3-CO2 present in the luminal bathing solution alone, proximal colon does not significantly acidify or alkalinize the serosal bathing solution. Addition of glucose (10 mM) to the luminal bathing solution abolished luminal alkalinization. Removal of HCO3 and CO2 from the serosal bathing solution or replacement of O2 with N2 also abolished luminal alkalinization. Acetazolamide (0.1 mM) added to both bathing solutions did not alter the rate of luminal alkalinization. Ion-replacement studies revealed that the alkalinization process was highly dependent on the presence of Na in the bathing solutions and much less dependent on the presence of Cl. Furthermore, ouabain (0.1 mM) significantly reduced luminal alkalinization. As in rabbit ileum, serosal epinephrine (0.1 mM) did not alter luminal alkalinization but increased serosal alkalinization by a Na-dependent mechanism. These results suggest that luminal alkalinization results from a Na-dependent, active transcellular HCO3 transport process and that a Na-dependent HCO3 absorptive process is activated by adrenergic stimuli.

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The Emerging Role of Soluble Adenylyl Cyclase in Primary Biliary Cholangitis

Digestive Diseases ◽

10.1159/000450914 ◽

2017 ◽

Vol 35 (3) ◽

pp. 217-223 ◽

Cited By ~ 4

Author(s):

Jung-Chin Chang ◽

Ulrich Beuers ◽

Ronald P.J. Oude Elferink

Keyword(s):

Bile Salt ◽

Adenylyl Cyclase ◽

Barrier Function ◽

Bile Salts ◽

Primary Biliary Cholangitis ◽

Biliary Cirrhosis ◽

Bicarbonate Secretion ◽

Soluble Adenylyl Cyclase ◽

Induced Apoptosis

Background: Primary biliary cholangitis (PBC; previously referred to as primary biliary cirrhosis) is a chronic fibrosing cholangiopathy with the signature of an autoimmune disease and features of intrahepatic cholestasis. Immunosuppressing treatments are largely unsuccessful. Responsiveness to ursodeoxycholic acid and reduced expression of anion exchanger 2 (AE2) on canalicular membranes and small bile ducts underline the importance of bicarbonate transportation in its disease mechanism. Soluble adenylyl cyclase (sAC; ADCY10) is an evolutionarily conserved bicarbonate sensor that regulates apoptosis, barrier function and TNF signaling. Key Messages: The biliary epithelium defends against the toxic bile by bicarbonate secretion and by maintaining a tight barrier. Passive diffusion of weak acid conjugates (e.g. bile salts and other toxins) across plasma membrane is pH-dependent. Reduced AE2 expression results in both reduced bicarbonate secretion and accumulation of bicarbonate in the cells. Increased intracellular bicarbonate leads to increased sAC activity, which regulates bile salt-induced apoptosis. Reduced bicarbonate secretion causes more bile salts to enter cells, which further increase sAC activity by releasing intracellular Ca2+ store. In vitro studies demonstrate that inhibition of sAC not only corrects sensitization to bile salt-induced apoptosis as a result of AE2 down-regulation but also prevents bile salt-induced apoptosis altogether. Targeting sAC is also likely to slow down disease progression by strengthening the barrier function of biliary epithelia and by reducing oxidative stress as a result of chronic inflammation. Conclusions: sAC is a potential therapeutic target for PBC. More in vitro and in vivo studies are needed to understand how sAC regulates bile salt-induced apoptosis and to establish its therapeutic value in PBC and other cholestatic cholangiopathies.

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P2Y receptors mediate Ca2+ signaling in duodenocytes and contribute to duodenal mucosal bicarbonate secretion

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.90314.2008 ◽

2009 ◽

Vol 296 (2) ◽

pp. G424-G432 ◽

Cited By ~ 22

Author(s):

Xiao Dong ◽

Eric James Smoll ◽

Kwang Hyun Ko ◽

Jonathan Lee ◽

Jimmy Yip Chow ◽

...

Keyword(s):

Short Circuit ◽

Short Circuit Current ◽

P2y Receptors ◽

Epithelial Cell Line ◽

Initial Increase ◽

Bicarbonate Secretion ◽

Duodenal Epithelium ◽

And Function

Since little is known about the role of P2Y receptors (purinoceptors) in duodenal mucosal bicarbonate secretion (DMBS), we sought to investigate the expression and function of these receptors in duodenal epithelium. Expression of P2Y2 receptors was detected by RT-PCR in mouse duodenal epithelium and SCBN cells, a duodenal epithelial cell line. UTP, a P2Y2-receptor agonist, but not ADP (10 μM), significantly induced murine duodenal short-circuit current and DMBS in vitro; these responses were abolished by suramin (300 μM), a P2Y-receptor antagonist, or 2-aminoethoxydiphenyl borate (2-APB; 100 μM), a store-operated channel blocker. Mucosal or serosal addition of UTP induced a comparable DMBS in wild-type mice, but markedly impaired response occurred in P2Y2 knockout mice. Acid-stimulated DMBS in vivo was significantly inhibited by suramin (1 mM) or PPADS (30 μM). Both ATP and UTP, but not ADP (1 μM), raised cytoplasmic-free Ca2+ concentrations ([Ca2+]cyt) with similar potencies in SCBN cells. ATP-induced [Ca2+]cyt was attenuated by U-73122 (10 μM), La3+ (30 μM), or 2-APB (10 μM), but was not significantly affected by nifedipine (10 μM). UTP (1 μM) induced a [Ca2+]cyt transient in Ca2+-free solutions, and restoration of external Ca2+ (2 mM) raised [Ca2+]cyt due to capacitative Ca2+ entry. La3+ (30 μM), SK&F96365 (30 μM), and 2-APB (10 μM) inhibited UTP-induced Ca2+ entry by 92, 87, and 94%, respectively. Taken together, our results imply that activation of P2Y2 receptors enhances DMBS via elevation of [Ca2+]cyt that likely results from an initial increase in intracellular Ca2+ release followed by extracellular Ca2+ entry via store-operated channel.

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