Effect ofE. coliheat-stable enterotoxin on colonic transport in guanylyl cyclase C receptor-deficient mice

2001 ◽  
Vol 280 (2) ◽  
pp. G216-G221 ◽  
Author(s):  
Alan N. Charney ◽  
Richard W. Egnor ◽  
Jesline T. Alexander-Chacko ◽  
Valentin Zaharia ◽  
Elizabeth A. Mann ◽  
...  
Keyword(s):  
Guanylyl Cyclase ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Proximal Colon ◽  
Guanylyl Cyclase C ◽  
Ussing Chambers ◽  
Heat Stable ◽  
Deficient Mice ◽  
Colonic Transport

We studied the functional importance of the colonic guanylyl cyclase C (GCC) receptor in GCC receptor-deficient mice. Mice were anesthetized with pentobarbital sodium, and colon segments were studied in Ussing chambers in HCO3−Ringer under short-circuit conditions. Receptor-deficient mouse proximal colon exhibited similar net Na+absorption, lower net Cl−absorption, and a negative residual ion flux ( JR), indicating net HCO3−absorption compared with that in normal mice. In normal mouse proximal colon, mucosal addition of 50 nM Escherichia coli heat-stable enterotoxin (STa) increased the serosal-to-mucosal flux of Cl−( Js→mCl) and decreased net Cl−flux ( JnetCl) accompanied by increases in short-circuit current ( Isc), potential difference (PD), and tissue conductance ( G). Serosal STa had no effect. In distal colon neither mucosal nor serosal STa affected ion transport. In receptor-deficient mice, neither mucosal nor serosal 500 nM STa affected electrolyte transport in proximal or distal colon. In these mice, 1 mM 8-bromo-cGMP produced changes in proximal colon Js→mCland JnetCl, Isc, PD, G, and JRsimilar to mucosal STa addition in normal mice. We conclude that the GCC receptor is necessary in the mouse proximal colon for a secretory response to mucosal STa.

Ion transport across the normal and CF neonatal murine intestine

1999 ◽  
Vol 277 (1) ◽  
pp. G167-G174 ◽  
Author(s):  
B. R. Grubb
Keyword(s):  
Intestinal Obstruction ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Proximal Colon ◽  
High Rate ◽  
Small Aperture ◽  
Ussing Chambers ◽  
Reduced Rate ◽  
Very High

Neonatal mice with cystic fibrosis (CF) exhibit a very high mortality due to intestinal obstruction localized primarily to the ileum and colon. It has been hypothesized that lack of Cl− secretion and possibly elevated Na+ absorption contribute to the gut problems in CF neonates. Therefore, intestines (ileum, proximal colon, and distal colon) from normal and CF day-old mouse pups were studied on ultra-small-aperture (0.0135 cm2) Ussing chambers. All three regions of the normal neonatal intestine responded to forskolin with an increase in short-circuit current, which was completely absent in the CF intestine. The neonatal distal colon exhibited a high rate of amiloride-sensitive electrogenic Na+ absorption, which did not differ between the normal and CF preparations. The ileum and proximal colon of both genotypes exhibited a small but significant electrogenic Na+ absorption. The neonatal proximal colon and ileum also exhibited electrogenic Na+-glucose cotransport, which was significantly greater in the normal compared with the CF ileum. In addition, all three intestinal regions exhibited electrogenic Na+-alanine cotransport, which was significantly reduced in two of the regions of the CF neonatal intestine. It is speculated that: 1) the reduced rate of Na+-nutrient cotransport in the CF intestine contributes to the lower rate of growth in CF pups, whereas 2) the elevated electrogenic Na+ absorption in the neonatal intestine, coupled with an inability to secrete Cl−, contributes to the intestinal obstruction in the CF pups.

Histamine augments colonic secretion in guinea pig distal colon

1990 ◽  
Vol 258 (3) ◽  
pp. G432-G439 ◽  
Author(s):  
Y. Z. Wang ◽  
H. J. Cooke ◽  
H. C. Su ◽  
R. Fertel
Keyword(s):  
Short Circuit ◽  
Nordihydroguaiaretic Acid ◽  
Short Circuit Current ◽  
Intestinal Secretion ◽  
Distal Colon ◽  
H2 Antagonist ◽  
Colonic Secretion ◽  
Set Up ◽  
Colonic Transport

We tested the hypothesis that the role of histamine in the control of intestinal secretion is mediated by prostaglandins (PGs). The effects of histamine on ion transport were examined in muscle-stripped sheets of mucosa/submucosa set up in flux chambers. Histamine evoked a transient concentration-dependent increase in short-circuit current (Isc) that was reduced by the Cl- transport inhibitor bumetanide. Histamine also caused the release of PGE2. The Isc response to histamine was reduced by indomethacin and piroxicam, which block PG formation, but not by nordihydroguaiaretic acid, which prevents production of lipoxygenase products. 2-Methylhistamine, but not dimaprit, evoked a concentration-dependent increase in Isc. The Isc response to histamine was reduced by the H1-blocker pyrilamine, but not by the H2-antagonist cimetidine. In addition to its direct effect, histamine augmented the responses of endogenously released neurotransmitters with and without indomethacin and hexamethonium. Tetrodotoxin (TTX) reduced the Isc response to 10(-3) M histamine. In the presence of TTX, exogenous histamine amplified the responses to PGs, vasoactive intestinal polypeptide, 2-chloroadenosine, bethanechol, and carbachol. These results suggest that histamine acts at H1-receptors on cells within the gut to mediate intestinal Cl- secretion in part by releasing PGs and by augmenting the actions of endogenously released neurotransmitters. Our results indicate that histamine has a role in the regulation of colonic transport function.

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.

Brain natriuretic peptide stimulates K and Cl secretion across porcine distal colon epithelium

1991 ◽  
Vol 260 (4) ◽  
pp. C750-C755 ◽  
Author(s):  
T. R. Traynor ◽  
S. M. O'Grady
Keyword(s):  
Brain Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Ringer Solution ◽  
Ussing Chambers ◽  
Cl Secretion ◽  
The Difference ◽  
Distal Colon Epithelium

Porcine distal colon epithelium was mounted in Ussing chambers and bathed with porcine Ringer solution. The serosal addition of brain natriuretic peptide (BNP; 50 nM) or atriopeptin III (AP-III; 500 nM) produced significant increases (50-75 microA/cm2) in short-circuit current (Isc). These increases in Isc were not inhibited by pretreatment with tetrodotoxin (TTX) or 5,8,11,14-eicosatetraynoic acid (ETYA). Analysis of concentration-response relationships revealed that BNP was 5.8-fold more potent than AP-III in stimulating the Isc. BNP and AP-III significantly increased the serosal-to-mucosal (S----M) Cl flux and reduced net Cl absorption by 38 and 41%, respectively. The BNP-stimulated S----M Cl flux was abolished when HCO3 was removed. In contrast, the vasoactive intestinal peptide (VIP)-stimulated S----M Cl flux was not affected by HCO3 replacement. In addition to their effects on Cl transport, BNP and AP-III increased net Rb secretion by 79 and 58%, respectively. BNP-stimulated Rb secretion was reduced by 76% after HCO3 replacement. These results indicate that natriuretic peptides stimulate K- and HCO3-dependent Cl secretion which is not present under basal conditions or after VIP stimulation. The difference in potency between BNP and AP-III suggests that ANP-B receptors may mediate their effects on ion transport in the porcine colon.

NaCl transport across equine proximal colon and the effect of endogenous prostanoids

1990 ◽  
Vol 259 (1) ◽  
pp. G62-G69 ◽  
Author(s):  
L. L. Clarke ◽  
R. A. Argenzio
Keyword(s):  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Proximal Colon ◽  
Nacl Transport ◽  
Apparent Lack ◽  
Ussing Chambers ◽  
Cl Secretion

In contrast to in vivo findings, the equine proximal colon fails to demonstrate significant net absorption of Na+ and Cl- under in vitro conditions. The present study was undertaken to determine if endogenous prostanoids are responsible for this apparent lack of ion transport. Proximal colonic tissues from ponies were preincubated in either normal Ringer solution or in Ringer containing 1 microM indomethacin and studied in Ussing chambers containing these solutions. Untreated colonic mucosa demonstrated negligible Na(+)-Cl- absorption in the basal state. In contrast, indomethacin-treated colon significantly absorbed Na+ and Cl-, primarily as the result of an equivalent increase in the mucosal-to-serosal flux of these ions. Preincubation of proximal colon in 0.1 mM ibuprofen-treated Ringer yielded similar results. Treatment of indomethacin colon with 1 mM mucosal amiloride eliminated net Na(+)-Cl- absorption without affecting the short-circuit current (Isc). The Isc in control tissue was significantly greater than in indomethacin-treated tissue and was reduced by 0.1 mM serosal furosemide. Serosal addition of 0.1 microM prostaglandin E2 or 10 mM serosal plus mucosal theophylline to indomethacin-treated tissues abolished net Na(+)-Cl- absorption and increased the Isc to levels indistinguishable from control. In contrast, control tissues were essentially unaffected by these secretagogues. These findings indicated that Na(+)-Cl- absorption in equine proximal colon was electroneutral (possibly involving Na(+)-H+ exchange) and that the tissue was capable of electrogenic Cl- secretion. However, under the in vitro conditions, basal ion transport was dominated by endogenous prostanoids that abolished Na(+)-Cl- absorption and elicited near-maximal electrogenic Cl- secretion.

Alterations of the VIP-stimulated cAMP pathway in rat distal colon after abdominal irradiation

2002 ◽  
Vol 282 (5) ◽  
pp. G835-G843 ◽  
Author(s):  
E. Morel ◽  
I. Dublineau ◽  
F. Lebrun ◽  
N. M. Griffiths
Keyword(s):  
Short Circuit ◽  
Major Change ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Cell Number ◽  
Rat Colon ◽  
Camp Accumulation ◽  
Ussing Chambers ◽  
Abdominal Irradiation ◽  
Vip Receptor

Ionizing radiation induces hyporesponsiveness of rat colonic mucosa to vasoactive intestinal peptide (VIP). Possible mechanisms responsible for this hyporesponsiveness of the cAMP communication pathway in rat colon were investigated. VIP- and forskolin-stimulated short-circuit current ( I sc) responses were studied after a 10-Gy abdominal irradiation in Ussing chambers as well as in single, isolated crypts. Adenylyl cyclase (AC) activity and VIP receptor characteristics were determined in mucosal membrane preparations. In addition, alterations in crypt morphology were studied. Impaired secretory responses to VIP and forskolin were observed 4 days after irradiation (decrease of 80%). cAMP analog-stimulated I scresponses were unchanged. In isolated crypts, VIP- and forskolin-stimulated cAMP accumulation was markedly reduced by 80 and 50%, respectively. VIP-stimulated AC activity and VIP receptor number were decreased in membrane preparations. No major change of cellularity was associated with these functional alterations. In conclusion, the decreased secretory responses to VIP of rat colon are associated with reduced cAMP accumulation, decreased AC activity, and diminution of VIP receptor numbers without a marked decrease of crypt cell number.

Development of L-glutamine-stimulated electroneutral sodium absorption in piglet jejunum

1990 ◽  
Vol 259 (1) ◽  
pp. G99-G107 ◽  
Author(s):  
J. M. Rhoads ◽  
E. O. Keku ◽  
L. E. Bennett ◽  
J. Quinn ◽  
J. G. Lecce
Keyword(s):  
Small Intestine ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Electrolyte Transport ◽  
Sodium Absorption ◽  
Nacl Transport ◽  
Ussing Chambers ◽  
Nacl Absorption ◽  
Intestinal Electrolyte Transport ◽  
Colonic Transport

Glutamine is the primary metabolic fuel of the small intestine. To determine the effects of glutamine on intestinal electrolyte transport, piglet (3 days to 3 wk old) jejunum was bathed in Ussing chambers in a buffer containing 10 mM serosal glucose, and the effects of different concentrations of mucosal L-glutamine and D-glucose on short-circuit current and transmucosal Na+ and Cl- transport were measured. Resting jejunum secreted Na+ and Cl- in an electrogenic manner. In contrast to mucosal D-glucose (30 mM), which promoted electrogenic Na+ absorption (1.8 mueq.cm-2.h-1), mucosal L-glutamine (30 mM) stimulated both Na+ (2.7 mueq.cm-2.h-1) and Cl- (2.2 mueq.cm-2.h-1) absorption. This NaCl-absorptive jejunal response depended on the presence of both Na+ and Cl-, did not appear until animals were greater than 7 days of age, and was not observed with glucose, phenylalanine, or mannitol. Serosal, as well as mucosal, glutamine (30 mM) promoted electroneutral NaCl absorption. A small electrogenic Na(+)-absorptive response to L-glutamine was also observed. The effect of L-glutamine on jejunal NaCl transport resembles that of other metabolic fuels on colonic transport; its mechanism remains to be determined. We conclude that glutamine promotes electroneutral salt absorption in the small intestine.

Taurodeoxycholate and the developing rabbit distal colon: absence of secretory effect

1987 ◽  
Vol 253 (4) ◽  
pp. G483-G488 ◽  
Author(s):  
G. D. Potter ◽  
R. Lester ◽  
S. M. Burlingame ◽  
P. A. Mitchell ◽  
K. L. Schmidt
Keyword(s):  
Ion Transport ◽  
Bile Acids ◽  
Phorbol Ester ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Fluid Secretion ◽  
Secretory Response ◽  
Ussing Chambers ◽  
Cl Secretion

Failure to absorb bile acids by the ileum leads to fluid secretion by the colon and diarrhea in adults. The infant ileum, however, does not actively transport bile acids. Therefore, we investigated the effect of taurodeoxycholic acid (TDCA) on ion transport in the colon of rabbits 7-10 days old. We mounted distal colon from infant and adult rabbits in modified Ussing chambers and exposed the mucosal or serosal surfaces to TDCA. In the adult, 50 microM TDCA produced an increase in short-circuit current (delta Isc = 1.0 +/- 0.3 mu eq . h-1 . cm-2, P less than 0.05) and Cl secretion. In the infant, the effect was different, Isc was reduced (delta Isc = -1.1 +/- 0.2 mu eq . h-1 . cm-2, P less than 0.01) and ion flux was not altered. Microscopy demonstrated that the infant epithelium was not significantly damaged by exposure to TDCA at these concentrations. The infant colon was, however, capable of a secretory response to a variety of agonists including theophylline, carbachol, bradykinin, serotonin, and 12,13-dibutyryl phorbol ester. The infant rabbit distal colon lacks a secretory response to TDCA during that period when the ileum cannot transport bile acids.

Cyclic nucleotide-gated cation channels mediate sodium and calcium influx in rat colon

2000 ◽  
Vol 278 (2) ◽  
pp. C336-C343 ◽  
Author(s):  
W. Qiu ◽  
B. Lee ◽  
M. Lancaster ◽  
W. Xu ◽  
S. Leung ◽  
...  
Keyword(s):  
Cyclic Nucleotide ◽  
Calcium Absorption ◽  
Calcium Influx ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Proximal Colon ◽  
Cation Channels ◽  
Rat Colon ◽  
Sodium Absorption

We found mRNA for the three isoforms of the cyclic nucleotide-gated nonselective cation channel expressed in the mucosal layer of the rat intestine from the duodenum to the colon and in intestinal epithelial cell lines in culture. Because these channels are permeable to sodium and calcium and are stimulated by cGMP or cAMP, we measured 8-bromo-cGMP-stimulated sodium-mediated short-circuit current ( I sc) in proximal and distal colon and unidirectional45Ca2+fluxes in proximal colon to determine whether these channels could mediate transepithelial sodium and calcium absorption across the colon. Sodium-mediated I sc, stimulated by 8-bromo-cGMP, were inhibited by dichlorobenzamil and l-cis-diltiazem, blockers of cyclic nucleotide-gated cation channels, suggesting that these ion channels can mediate transepithelial sodium absorption. Sodium-mediated I sc and net transepithelial45Ca2+absorption were stimulated by heat-stable toxin from Escherichia coli that increases cGMP. Addition of l-cis-diltiazem inhibited the enhanced transepithelial absorption of both ions. These results suggest that cyclic nucleotide-gated cation channels simultaneously increase net sodium and calcium absorption in the colon of the rat.

Alterations in airway ion transport in NKCC1-deficient mice

2001 ◽  
Vol 281 (2) ◽  
pp. C615-C623 ◽  
Author(s):  
B. R. Grubb ◽  
A. J. Pace ◽  
E. Lee ◽  
B. H. Koller ◽  
R. C. Boucher
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Airway Disease ◽  
Treatment Protocols ◽  
Anion Secretion ◽  
Ussing Chambers ◽  
Adult Mice ◽  
Ion Substitution ◽  
Deficient Mice

Airways of Na+-K+-2Cl−(NKCC1)-deficient mice (−/−) were studied in Ussing chambers to determine the role of the basolateral NKCC1 in transepithelial anion secretion. The basal short-circuit current ( I sc) of tracheae and bronchi from adult mice did not differ between NKCC1−/− and normal mice, whereas NKCC1−/− tracheae from neonatal mice exhibited a significantly reduced basal I sc. In normal mouse tracheae, sensitivity to the NKCC1 inhibitor bumetanide correlated inversely with the age of the mouse. In contrast, tracheae from NKCC1−/− mice at all ages were insensitive to bumetanide. The anion secretory response to forskolin did not differ between normal and NKCC1−/− tissues. However, when larger anion secretory responses were induced with UTP, airways from the NKCC1−/− mice exhibited an attenuated response. Ion substitution and drug treatment protocols suggested that HCO[Formula: see text]secretion compensated for reduced Cl− secretion in NKCC1−/− airway epithelia. The absence of spontaneous airway disease or pathology in airways from the NKCC1−/− mice suggests that the NKCC1 mutant mice are able to compensate adequately for absence of the NKCC1 protein.

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