Concentration-dependent effects of disulfonic stilbenes on colonic chloride transport

1986 ◽  
Vol 250 (1) ◽  
pp. G44-G49 ◽  
Author(s):  
P. L. Smith ◽  
S. K. Sullivan ◽  
R. D. McCabe
Keyword(s):  
Colonic Mucosa ◽  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Bathing Solution ◽  
Ussing Chambers ◽  
Unidirectional Fluxes ◽  
Dose Dependent ◽  
Disulfonic Stilbenes

Stripped rabbit colonic mucosa was studied in vitro in Ussing chambers to determine effects of the disulfonic stilbenes 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonate (SITS) and 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) and the diuretic furosemide on unidirectional and net Cl fluxes. Results from these studies reveal that SITS (1 mM) added to either the serosal or mucosal bathing solution reduced both unidirectional Cl fluxes with no significant change in net Cl flux. The effects of SITS do not appear to be mediated by an effect on the shunt permeability since SITS (1 mM) did not alter either the intercept or slope of the Na concentration dependence of the serosal-to-mucosal Na flux. Furosemide (1 mM) decreased the serosal-to-mucosal Cl flux without altering short-circuit current (Isc) when added to the luminal bathing solution and reduced both unidirectional fluxes and increased Isc when added to the serosal bathing solution. DIDS (0.5 mM) added to the luminal bathing solution did not alter unidirectional Cl fluxes or Isc. However, serosal addition of DIDS produced dose-dependent changes in Cl transport. At 5 microM DIDS reduced the mucosal-to-serosal Cl flux without altering the serosal-to-mucosal flux or Isc. At 50 microM DIDS reduced the mucosal-to-serosal Cl flux and increased Isc, and at 0.5 mM DIDS increased the serosal-to-mucosal Cl flux, reduced the mucosal-to-serosal Cl flux, and increased Isc and transepithelial conductance. The effect of 0.5 mM DIDS on Isc was reduced by Ca removal from the serosal bathing solution and by the loop diuretics furosemide and bumetanide.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of sulfidopeptide leukotrienes D4 and E4 on ileal ion transport in vitro in the rat and rabbit

1988 ◽  
Vol 255 (2) ◽  
pp. G175-G183 ◽  
Author(s):  
P. L. Smith ◽  
D. P. Montzka ◽  
G. P. McCafferty ◽  
M. A. Wasserman ◽  
J. D. Fondacaro
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Bathing Solution ◽  
Na Transport ◽  
Rabbit Ileum ◽  
Rat Ileum ◽  
Ussing Chambers ◽  
Meclofenamic Acid ◽  
Acid Metabolites

Effects of leukotrienes D4 and E4 (LTD4 and LTE4) on electrolyte transport were examined, employing stripped segments of rat and rabbit ileum mounted in Ussing chambers. Addition of LTD4 or LTE4 to the serosal but not the mucosal bathing solution elicited a transient increase in short-circuit current (Isc) with maximal responses seen at 10(-5) M and 10(-8) M in rat and rabbit respectively and a sustained decrease in transepithelial conductance (Gt) in the rat only. In the rat, Cl replacement, reduction of bathing solution [Ca2+] to 1 microM or pretreatment with 1 microM indomethacin or meclofenamic acid inhibited the LTD4- or LTE4-induced Isc changes with no effect on the decrease in Gt. LTD4 (10 microM) transiently increased net Cl secretion and produced a sustained decrease in both unidirectional and net Na transport and mucosal-to-serosal Cl flux in rat ileum. The decrease in unidirectional Na fluxes is accounted for predominantly by a change in the potential independent flux of Na. These results suggest that the increase in Isc in both rat and rabbit is mediated by arachidonic acid metabolites, whereas the decrease in Gt and net Na absorption in rat ileum is mediated by a cyclooxygenase-independent pathway.

Sodium dependence of luminal alkalinization by rabbit ileal mucosa

1985 ◽  
Vol 249 (3) ◽  
pp. G358-G368 ◽  
Author(s):  
P. L. Smith ◽  
M. A. Cascairo ◽  
S. K. Sullivan
Keyword(s):  
Prostaglandin E1 ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Bathing Solution ◽  
Ileal Mucosa ◽  
Adrenergic Agents ◽  
Ussing Chambers ◽  
Sodium Removal ◽  
Ph Stat

Stripped rabbit ileal mucosa was studied in vitro in Ussing chambers under short-circuit conditions using the pH-stat technique to determine basal rates of luminal alkalinization; the contribution of the shunt pathway to the alkalinization process; the effects of Na, Cl, or HCO3 removal from the bathing solutions on luminal alkalinization; and the effects of epinephrine, ouabain, 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS), acetazolamide, prostaglandin E1 (PGE1), A23187, sugars, or amino acids on the alkalinization process. Results from these studies reveal that, under basal conditions, the rate of luminal alkalinization accounts for 81% of the basal short-circuit current (Isc), although there was no correlation between the rate of alkalinization and Isc. The contribution of the shunt to the alkalinization process accounts for less than 10% of the mucosal-to-serosal HCO3 flux. Removal of Cl from the bathing solutions increased the rate of luminal alkalinization and decreased Isc. Sodium removal from the bathing solutions reduced both Isc and the rate of luminal alkalinization. Addition of DIDS to the luminal or serosal bathing solution reduced luminal alkalinization less than 30%. Acetazolamide, PGE1, and A23187 were all without effect on luminal alkalinization. Addition of 3-O-methyl-D-glucose or L-alanine to the luminal bathing solution did not alter luminal alkalinization but increased Isc, D-Glucose added to the luminal bathing solution reduced luminal alkalinization. This effect appears to result from metabolic acid production since 1) it is not seen with L-alanine or 3-O-methyl-D-glucose; 2) in the absence of HCO3 in the bathing solutions, D-glucose increased luminal acidification; and 3) luminal addition of fructose also reduced the rate of luminal alkalinization. Addition of epinephrine to the serosal bathing solution stimulates a Na-dependent serosal alkalinization process. These results suggest that luminal alkalinization results from Na-dependent, transcellular HCO3 transport and that a Na-dependent, HCO3 absorptive process is stimulated by adrenergic agents.

Colonic potassium and chloride secretion: role of cAMP and calcium

1985 ◽  
Vol 248 (1) ◽  
pp. G103-G109 ◽  
Author(s):  
R. D. McCabe ◽  
P. L. Smith
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Bathing Solution ◽  
Ionophore A23187 ◽  
Ussing Chambers ◽  
Cl Secretion ◽  
Intracellular Ca

Stripped rabbit colonic mucosa was studied in vitro in Ussing chambers to further investigate the role of Ca in regulating K and Cl secretion stimulated by the divalent cation ionophore A23187, prostaglandin E1 (PGE1), or 8-bromo-cAMP (8BrcAMP). To assess the effects of these secretagogues on the paracellular shunt permeability, we measured the Na concentration dependence of the serosal-to-mucosal Na flux in the absence or presence of these stimuli. Results from these studies reveal that changes in net K and Cl secretion produced by secretory stimuli cannot be accounted for by a change in shunt permeability. The possible involvement of Ca in the secretory response of the colon to these stimuli was investigated by measuring the changes in Cl and K transport elicited by A23187, PGE1, or 8BrcAMP in the absence or presence of trifluoperazine (10(-4) M) added to the serosal bathing solution. Trifluoperazine alone did not significantly alter basal Na or Cl fluxes or short-circuit current (Isc) but did decrease transepithelial conductance (Gt) and the serosal-to-mucosal K flux. Pretreatment of the tissues with trifluoperazine significantly reduced or abolished the changes in K fluxes elicited by A23187, 8BrcAMP, or PGE1 without altering the changes in Cl transport, Isc, and Gt. These results suggest that K secretion induced by these secretagogues involves an increase in intracellular Ca concentration and may be mediated by calmodulin.

Protein kinase C potentiates cAMP-stimulated mouse duodenal mucosal bicarbonate secretion in vitro

2004 ◽  
Vol 286 (5) ◽  
pp. G814-G821 ◽  
Author(s):  
Bi-Guang Tuo ◽  
Jimmy Y. C. Chow ◽  
Kim E. Barrett ◽  
Jon I. Isenberg
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Duodenal Mucosa ◽  
Bicarbonate Secretion ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Ussing Chambers ◽  
Duodenal Bicarbonate Secretion

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.

Effect of pH on chloride absorption in the flounder intestine

1988 ◽  
Vol 255 (2) ◽  
pp. G247-G252 ◽  
Author(s):  
A. N. Charney ◽  
J. I. Scheide ◽  
P. M. Ingrassia ◽  
J. A. Zadunaisky
Keyword(s):  
Small Intestine ◽  
Short Circuit ◽  
Ph Effect ◽  
Short Circuit Current ◽  
Bathing Solution ◽  
Solution Ph ◽  
Transport Pathway ◽  
Ussing Chambers ◽  
Chloride Absorption ◽  
In Series

Chloride absorption in the small intestine of the winter flounder, Pseudopleuronectes americanus, is reported to be sensitive to ambient pH. We studied this sensitivity in isolated stripped intestinal mucosa mounted in modified Ussing chambers. Unidirectional 36Cl fluxes (JClm----s, JCls----m) were measured under short-circuited conditions in bathing solutions containing various combinations of HCO3- (0-20 mM), partial pressure of CO2 (0-36 mmHg), and pH (6.77-7.85). We found that JClm----s, net 36Cl flux (JClnet), and short-circuit current (Isc) increased and JCls----m decreased predominately in response to increases in bathing solution pH. There was a linear relationship between pH and both JClnet (r = 0.92, P less than 0.01) and Isc (r = 0.96, P less than 0.005) between pH 6.77 and 7.74. The pH effect was completely reversible, did not require either CO2 or HCO3-, and was not affected by the presence of mucosal barium at 1 mM. Mucosal bumetanide (0.1 mM) completely inhibited the pH effect. These data suggest that the process by which Cl- is absorbed in the flounder intestine is sensitive to pH. The data do not indicate whether pH affects Na+-K+-2Cl- cotransport or a Cl- transport pathway in series with this process. The direction of Cl- absorption in response to pH contrasts with inverse relation of pH and Cl- absorption in mammalian small intestine.

Mechanisms of sodium and chloride transport across equine tracheal epithelium

1990 ◽  
Vol 259 (6) ◽  
pp. L459-L467 ◽  
Author(s):  
G. J. Tessier ◽  
T. R. Traynor ◽  
M. S. Kannan ◽  
S. M. O3'Grady
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Short Circuit Current ◽  
Ringer Solution ◽  
Tracheal Epithelium ◽  
Ussing Chambers ◽  
Cl Secretion ◽  
Cotransport System ◽  
Ethanesulfonic Acid

Equine tracheal epithelium, stripped of serosal muscle, mounted in Ussing chambers, and bathed in plasmalike Ringer solution generates a serosa-positive transepithelial potential of 10–22 mV and a short-circuit current (Isc) of 70–200 microA/cm2. Mucosal amiloride (10 microM) causes a 40–60% decrease in Isc and inhibits the net transepithelial Na flux by 95%. Substitution of Cl with gluconate resulted in a 30% decrease in basal Isc. Bicarbonate substitution with 20 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid decreased the Isc by 21%. The Cl-dependent Isc was inhibited by serosal addition of 1 mM amiloride. Bicarbonate replacement or serosal amiloride (1 mM) inhibits the net Cl flux by 72 and 69%, respectively. Bicarbonate replacement significantly reduces the effects of serosal amiloride (1 mM) on Isc, indicating its effect is HCO3 dependent. Addition of 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP; 100 microM) causes a 40% increase in Isc. This effect is inhibited by subsequent addition of 10 microM serosal bumetanide. Bumetanide (10 microM) reduces net Cl secretion following stimulation with 8-BrcAMP (100 microM). Serosal addition of BaCl2 (1 mM) causes a reduction in Isc equal to that following Cl replacement in the presence or absence of 100 microM cAMP. These results suggest that 1) Na absorption depends on amiloride-inhibitable Na channels in the apical membrane, 2) Cl influx across the basolateral membrane occurs by both a Na-H/Cl-HCO3 parallel exchange mechanism under basal conditions and by a bumetanide-sensitive Na-(K?)-Cl cotransport system under cAMP-stimulated conditions, and 3) basal and cAMP-stimulated Cl secretion depends on Ba-sensitive K channels in the basolateral membrane.

Neuromodulation of ion transport in porcine distal colon: NPY reduces secretory actions of leukotrienes

1995 ◽  
Vol 269 (2) ◽  
pp. R426-R431 ◽  
Author(s):  
T. R. Traynor ◽  
D. R. Brown ◽  
S. M. O'Grady
Keyword(s):  
Ion Transport ◽  
Colonic Mucosa ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Effective Concentration ◽  
Leukotriene C4 ◽  
Ussing Chambers ◽  
Cl Secretion ◽  
Half Maximal Effective Concentration

Electrical transmural stimulation (ETS) was used to examine the neuroregulation of electrolyte transport in the porcine distal colon. ETS of the colonic mucosa-submucosa mounted in Ussing chambers produced rapid and transient increases in short-circuit current (Isc) that were inhibited 36% by serosal bumetanide, suggesting that a portion of the response may be attributed to Cl secretion. ETS actions were dependent upon stimulus intensity and frequency and were inhibited by tetrodotoxin and omega-conotoxin. Prazosin and pyrilamine had no effect on the mucosal responses to ETS, whereas atropine reduced the responses by 32%. Neuropeptide Y (NPY) also reduced the mucosal responses to ETS up to 60% (half-maximal effective concentration = 17 nM). In addition, the effects of leukotriene C4, previously shown to stimulate Cl secretion via a neuronal pathway, were also inhibited by NPY. These results indicate that cholinergic submucosal neurons play a role in the regulation of epithelial ion transport and that NPY acts as an inhibitory neuromodulator, particularly on leukotriene-sensitive neurons in the porcine distal colon.

Effect of the thiol-oxidizing agent diamide on NH2Cl-induced rat colonic electrolyte secretion

1993 ◽  
Vol 265 (1) ◽  
pp. C166-C170 ◽  
Author(s):  
H. Tamai ◽  
J. F. Kachur ◽  
M. B. Grisham ◽  
M. W. Musch ◽  
E. B. Chang ◽  
...  
Keyword(s):  
Colonic Mucosa ◽  
Short Circuit ◽  
Chloride Ion ◽  
Short Circuit Current ◽  
Rat Colon ◽  
Maximal Effect ◽  
Oxidizing Agent ◽  
Maximal Increase ◽  
Ussing Chambers ◽  
Electrolyte Secretion

The granulocyte-derived oxidant, monochloramine (NH2Cl), is known to stimulate chloride ion secretion in rat distal colonic mucosa mounted in Ussing chambers, through mechanisms that are sensitive and insensitive to tetrodotoxin (TTX). The possible role of intracellular thiols, in the mechanism of action of NH2Cl as a secretagogue, was evaluated with the thiol-oxidizing agent diamide and by measuring tissue sulfhydryl levels in response to NH2Cl. Serosal exposure to the antioxidant glutathione (0.25 mM), 5 min before NH2Cl (50 microM) addition, decreased the maximal effect of 50 microM NH2Cl on short-circuit current (Isc). The NH2Cl-stimulated increase in Isc was not affected by mucosal amiloride (5 microM). Pretreatment with 0.1 mM diamide shortened the lag period before the increase in Isc in response to NH2Cl, but it did not affect the maximal increase in Isc. Although TTX (0.5 microM) increased the lag time for achievement of the maximal Isc response to NH2Cl, the neurotoxin did not inhibit the effect of diamide, suggesting that diamide acts primarily on the nonneural component of NH2Cl-stimulated secretion. Incubation of colonic mucosa with NH2Cl, with or without diamide, decreased cellular acid-soluble sulfhydryl concentrations. Taken together, the results support a role for epithelial cell thiols in NH2Cl-stimulated electrolyte secretion by the rat colon.

Effect of acetazolamide on sodium and chloride transport by in vitro rabbit ileum

1975 ◽  
Vol 228 (6) ◽  
pp. 1808-1814 ◽  
Author(s):  
HN Nellans ◽  
RA Frizzell ◽  
SG Schultz
Keyword(s):  
Cyclic Amp ◽  
Chloride Transport ◽  
Short Circuit ◽  
Electrical Potential ◽  
Direct Interaction ◽  
Short Circuit Current ◽  
Electrical Potential Difference ◽  
Membrane Component ◽  
Rabbit Ileum

Acetazolamide (8 mM) aboishes active Cl absorption and inhibits but does not abolish active Na absorption by stripped, short-circuited rabbit ileum. These effects are not accompanied by significant changes in the transmural electrical potential difference or short-circuit current. Studies of the undirectional influxes of Na andCl indicate that acetazolamide inhibits the neutral, coupled NaCl influx process at the mucosal membranes. This action appears to explain the observed effect of acetazolamide on active, transepithelial Na and Cl transport. Acetazolamide did not significantly inhibit either spontaneous or theophylline-induced Cl secretion by this preparation, suggesting that the theophylline-induced secretion may not simply be due tothe unmasking of a preexisting efflux process when the neutral influx mechanism is inhibited by theophylline. Finally, inhibition of the neutral NaCl influx process by acetazolamide does not appear to be attributable to an inhibition of endogenous HCO3production or an elevation in intracellular cyclic-AMP levels. Instead, it appearstheat the effect of acetazolamide is due to a direct interaction with a membrane component involved in the coupled influx process.

Water and electrolyte transport by rabbit esophagus

1975 ◽  
Vol 229 (2) ◽  
pp. 438-443 ◽  
Author(s):  
DW Powell ◽  
SM Morris ◽  
DD Boyd
Keyword(s):  
Sodium Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Electrolyte Transport ◽  
Potential Difference ◽  
Sodium Absorption ◽  
Bathing Solution ◽  
Electrical Potential Difference

The nature of the transmural electrical potential difference and the characteristics of water and electrolyte transport by rabbit esophagus were determined with in vivo and in vitro studies. The potential difference of the perfused esophagus in vivo was -28 +/- 3 mV (lumen negative). In vitro the potential difference was -17.9 +/- 0.6 mV, the short-circuit current 12.9 +/- 0.6 muA/cm2, and the resistance 1,466 +/- 43 ohm-cm2. Net mucosal-to-serosal sodium transport from Ringer solution in the short-circuited esophagus in vitro accounted for 77% of the simultaneously measured short-circuit current and net serosal-to-mucosal chloride transport for 14%. Studies with bicarbonate-free, chloride-free, and bicarbonate-chloride-free solutions suggested that the net serosal-to mucosal transport of these two anions accounts for the short-circuit current not due to sodium absorption. The potential difference and short-circuit current were saturating functions of bathing solution sodium concentration and were inhibited by serosal ouabain and by amiloride. Thus active mucosal-to-serosal sodium transport is the major determinant of the potential difference and short-circuit current in this epithelium.

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