[15N]- and [14C]glutamine fluxes across rabbit ileum in experimental bacterial diarrhea

1992 ◽  
Vol 262 (2) ◽  
pp. G312-G318 ◽  
Author(s):  
S. K. Nath ◽  
P. Dechelotte ◽  
D. Darmaun ◽  
M. Gotteland ◽  
M. Rongier ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Rabbit Ileum ◽  
Diarrheagenic Escherichia Coli ◽  
Nacl Absorption ◽  
Cl Transport ◽  
Stimulation Of ◽  
Bacterial Diarrhea

L-Glutamine (Gln) fluxes and the effects of Gln on Na and Cl transport were studied across the ileum of healthy and rabbit diarrheagenic Escherichia coli (RDEC-1)-infected weanling rabbits. Stable ([alpha-15N]Gln) and radioisotopic ([U-14C]Gln) tracers provided identical estimates of Gln transport both in healthy (H) and infected (I) rabbits. RDEC-1 infection, however, decreased net Gln flux [Jnet[14C]Gln = 682 +/- 147 (H) vs. 278 +/- 63 (I); Jnet[15N]Gln = 739 +/- 160 vs. 225 +/- 110 nmol.h-1.cm-2] due to a reduction in mucosal-to-serosal flux. After addition of Gln, increases in net Na absorption [delta Jnet[15N]Gln = 1.87 +/- 0.45 (H) vs. 0.70 +/- 0.27 (I) microeq.h-1.cm-2] and short-circuit current (delta Isc) [1.80 +/- 0.40 (H) vs. 0.74 +/- 0.14 (I) microeq.h-1.cm-2] were also reduced in infected rabbits. Addition of glucose after Gln, however, stimulated Na absorption further. These results indicate that 1) Gln is actively absorbed as intact Gln molecule across rabbit ileum; 2) Gln stimulates an electrogenic Na absorption in a 1:2 ratio that may be further stimulated by glucose; and 3) in RDEC-1 infection electroneutral NaCl absorption, intact Gln absorption, and electrogenic stimulation of Na absorption by glutamine are reduced.

Chemotactic peptide effects on intestinal electrolyte transport

1990 ◽  
Vol 259 (6) ◽  
pp. G947-G954
Author(s):  
T. A. Barrett ◽  
M. W. Musch ◽  
E. B. Chang
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Arachidonic Acid Metabolism ◽  
Chemotactic Peptide ◽  
Rabbit Ileum ◽  
Intact Tissue ◽  
Microsomal Membranes ◽  
36Cl Fluxes ◽  
Stimulation Of

The bacterial-derived chemotactic peptide N-formylmethionyl-leucyl-phenylalanine (fMLP) increases short-circuit current (Isc) and arachidonic acid metabolism (AAM) in rabbit ileum and distal colon. Serosal (s) or mucosal (m) addition of fMLP transiently increases Isc. Half-maximally effective dose and maximal increases in Isc were 32 nM and 84 microA/cm2 in ileum and 234 nM and 80 microA/cm2 in colon, respectively. Piroxicam, a cyclooxygenase inhibitor, diminished the Isc response by 97% in colon and 69% in ileum. Changes in Isc were dependent on Cl- and HCO3- in the bathing media. In ileum, fMLP inhibited m-to-s 36Cl- fluxes and stimulated s-to-m 36Cl- fluxes. These changes in Cl- flux were also inhibited by piroxicam. fMLP stimulated prostaglandin E2 (PGE2) release in intact tissue and in isolated subepithelial components. Increased tissue adenosine 3',5'-cyclic monophosphate levels were detected in intact tissue but not in isolated components. Previous desensitization of ileum to PGE1 inhibited fMLP stimulation of Isc in ileum by 88%. Desensitization to fMLP in ileum failed to alter the effect of PGE1 (10 microM) on Isc. In isolated microsomal membranes of ileal enterocytes, fMLP binding sites could not be demonstrated, suggesting that fMLPs action was initially mediated via stimulation of nonepithelial cell cyclooxygenase activity. The above results indicate that fMLP stimulates net secretion in both ileum and colon probably by the activation of AAM.

cGMP modulation of ileal ion transport: in vitro effects of Escherichia coli heat-stable enterotoxin

1982 ◽  
Vol 243 (1) ◽  
pp. G36-G41 ◽  
Author(s):  
S. Guandalini ◽  
M. C. Rao ◽  
P. L. Smith ◽  
M. Field
Keyword(s):  
Escherichia Coli ◽  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Rabbit Ileum ◽  
Heat Stable ◽  
Transport Effects ◽  
In Vitro Effects ◽  
Nonadditive Effects

Diarrheagenic strains of Escherichia coli have been shown to produce a heat-stable enterotoxin (ST) that simulates guanylate cyclase, increases short-circuit current (Isc), and inhibits active Cl absorption in the intestine. In rabbit ileum, the ion transport effects are smaller than those produced by cAMP-related agonists. Because ST may be a selective cGMP agonist, we further explored its mode of action in rabbit ileum. ST inhibits net Na and net Cl absorption. ST also inhibits the same fraction of Cl influx across the brush border that theophylline inhibits. At maximal doses, ST and 8-bromo-cGMP (8-Br-cGMP) had nearly equal, nonadditive effects of Isc that were about 66% of that produced by 8-Br-cAMP. ST increased mucosal cGMP concentration 16-fold, whereas epinephrine, an inhibitor of secretion, increased cGMP concentration by only 30%. This is insufficient to alter ion transport because doses of ST that increased cGMP concentration by 100% failed to alter Cl fluxes. Furthermore, epinephrine did not increase cGMP concentration in isolated enterocytes. We conclude that 1) cGMP mediates ST effects on ion transport, and 2) although ST and cAMP-related agonists have the same antiabsorptive effects, ST is less effective in stimulating electrogenic Cl secretion.

Effect of serotonin on active electrolyte transport in rabbit ileum, gallbladder, and colon

1980 ◽  
Vol 239 (6) ◽  
pp. G463-G472 ◽  
Author(s):  
M. Donowitz ◽  
Y. H. Tai ◽  
N. Asarkof
Keyword(s):  
Maximum Concentration ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Electrolyte Transport ◽  
Rabbit Ileum ◽  
Rabbit Gallbladder ◽  
Epithelial Sheets ◽  
Dose Dependent ◽  
Stimulation Of

The effect of serotonin on active electrolyte transport was evaluated in vitro in epithelial sheets of rabbit ileum, gallbladder, and colon under short-circuited conditions. Serotonin added to the serosal surface of rabbit ileum caused a dose-dependent short-lived increase in short-circuit current and a more prolonged equal effect on net Na and Cl fluxes. The latter consisted primarily of inhibition of mucosal-to-serosal fluxes of both Na and Cl. In addition serosal serotonin decreased ileal Na influx from the mucosal solution into the epithelium, suggesting an effect on Na absorption. Serotonin did not alter all aspects of ileal absorptive function and did not affect glucose-dependent Na absorption. Consistent with serotonin acting by inhibiting NaCl absorption in the ileum, serotonin induced equal inhibition of net Na and Cl absorption in rabbit gallbladder (which has a linked Na and Cl absorptive process) but had no effect on rabbit colon (which lacks a linked Na and Cl absorptive process). In addition, adenosine 3',5'-cyclic monophosphate and serotonin both appeared to alter the same ileal NaCl absorptive process, since following stimulation of ileal secretion with the maximum concentration of theophylline, addition of serotonin did not cause any further effects.

L-glutamine with D-glucose stimulates oxidative metabolism and NaCl absorption in piglet jejunum

1992 ◽  
Vol 263 (6) ◽  
pp. G960-G966 ◽  
Author(s):  
J. M. Rhoads ◽  
E. O. Keku ◽  
J. P. Woodard ◽  
S. I. Bangdiwala ◽  
J. G. Lecce ◽  
...  
Keyword(s):  
Oxidative Metabolism ◽  
Carbonic Acid ◽  
Apical Membrane ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Glutamine Metabolism ◽  
Nacl Absorption ◽  
The Relationship ◽  
Stimulation Of

To explore the relationship between intestinal fluid absorption and oxidative metabolism, we measured the effects of amino acids and glucose on piglet jejunal ion transport and oxygen consumption (QO2) in vitro. Jejunal QO2 was stimulated by L-glutamine and D-glucose but not by the nonmetabolizable organic solutes methyl beta-D-glucoside or L-phenylalanine. QO2 was maximally enhanced by the combination of D-glucose and L-glutamine (5 mM). Even though 5 mM L-glutamine was previously found to be insufficient to stimulate NaCl absorption, 5 mM L-glutamine enhanced jejunal NaCl flux when combined with equimolar mucosal D-glucose. Either D-glucose or methyl beta-D-glucoside caused an increase in short-circuit current (Isc), an increase in Na+ absorption in excess of Isc, and a decrease in Cl- secretion, when L-glutamine was substituted for D-glucose (10 mM) on the serosal side. This relationship suggests that mucosal sugars, if combined with L-glutamine, enhance neutral NaCl absorption as well as electrogenic Na+ flow. (Aminooxy)acetate, an inhibitor of alanine aminotransferase, abolished the stimulation of QO2 and the NaCl-absorptive response to L-glutamine. We conclude that the oxidative metabolism fueled by L-glutamine is linked to a NaCl-absorptive mechanism in the intestine. We propose that the CO2 produced by glutamine metabolism yields carbonic acid, which dissociates to H+ and HCO3-, which may stimulate parallel antiports in the apical membrane.

Na and Cl transport and short-circuit current in rabbit ileum

1977 ◽  
Vol 31 (1) ◽  
pp. 189-204 ◽  
Author(s):  
Yuan-Heng Tai ◽  
Jehan-F. Desjeux ◽  
Giustina Danisi ◽  
Peter F. Curran
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Rabbit Ileum ◽  
Cl Transport

CFTR is required for cAMP inhibition of intestinal Na+ absorption in a cystic fibrosis mouse model

1996 ◽  
Vol 270 (2) ◽  
pp. G259-G267 ◽  
Author(s):  
L. L. Clarke ◽  
M. C. Harline
Keyword(s):  
Cystic Fibrosis ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Similar Rate ◽  
Transmembrane Conductance Regulator ◽  
Cl Secretion ◽  
Nacl Absorption ◽  
Flux Measurements ◽  
Camp Stimulation ◽  
Stimulation Of

Acute adenosine 3',5'-cyclic monophosphate (cAMP) stimulation of intestinal epithelium induces net transepithelial Cl- secretion and inhibits neutral coupled NaCl absorption. To investigate the role that the cystic fibrosis transmembrane conductance regulator (CFTR) plays in these events, we measured bioelectric changes and radioisotopic NaCl flux across jejunal tissues from gene-targeted cftr "knockout" mice [cftr(-/-) homozygotes] and their normal littermates [cftr(+/+) homozygotes and cftr(+/-) heterozygotes]. Before stimulation, the short-circuit current (Isc, an index of Cl- secretion) of the cftr(-/-) jejunum was essentially zero and significantly less than in the cftr(+/+) or cftr(+/-) intestine. Acute cAMP stimulation had little effect on the bioelectric parameters of the cftr(-/-) intestine but induced a marked increase of Isc and decrease of total tissue conductance in both the cftr(+/+) and cftr(+/-) intestine. Differences in the magnitude of the cAMP-induced Isc between the cftr(+/+) and cftr(+/-) intestine were only observed when the cell-to-lumen anion concentration gradient was maximized by removal of permeant anions from the luminal bath. Radioisotope flux measurements revealed that Na+ and Cl- were absorbed equally across the cftr(-/-) jejunum under basal conditions. In cftr(+/+) and cftr(+/-) intestine, Na+ was absorbed at a similar rate, but net Cl- absorption was reduced from that in cftr(-/-) intestine by an amount approximating the Isc. Acute cAMP stimulation of the cftr(+/+) and cftr(+/-) intestine abolished net NaCl absorption and induced electrogenic Cl- secretion. In contrast, net NaCl absorption was unchanged from the preceding flux period in the cftr(-/-) jejunum. The data suggest that CFTR not only mediates cAMP-induced transepithelial Cl- secretion but is also required for cAMP inhibition of neutral NaCl absorption in the intestine.

Effects of calcium antagonist TMB-8 on active Na and Cl transport in rabbit ileum

1986 ◽  
Vol 250 (5) ◽  
pp. G691-G697 ◽  
Author(s):  
M. Donowitz ◽  
S. Cusolito ◽  
G. W. Sharp
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Electrolyte Transport ◽  
Intracellular Camp ◽  
Bathing Solution ◽  
Rabbit Ileum ◽  
Camp Content ◽  
Cl Transport ◽  
Transport Effects ◽  
Intracellular Camp Content

The effects of 3,4,5-trimethoxybenzoate 8-(N,N-diethylamino)octyl ester (TMB-8), an agent that traps calcium within intracellular stores, were studied on active electrolyte transport in rabbit ileum under basal conditions and after altering transport by increasing the intracellular cAMP content or by exposure to two agonists that act by altering intracellular Ca2+ (carbachol and serotonin). TMB-8 decreased the ileal short-circuit current and increased active Na and Cl absorption by increasing the mucosal-to-serosal Na and Cl fluxes. These effects were reversed by increasing the bathing solution Ca2+ to 4 mM, a concentration that itself did not alter basal ileal transport. The maximum glucose- and amino acid (alanine)-induced increase in Na absorption in the ileum was not affected by TMB-8. The effects on basal transport of TMB-8 were not associated with a change in 45Ca2+ entry across the ileal serosal surface. TMB-8 did not alter cAMP-induced secretion, as judged by its lack of effect on the increase in short-circuit current caused by 8-bromo-cAMP (10(-4) M). TMB-8 totally prevented the transport effects of carbachol but did not inhibit the effects of serotonin. These data suggest a role for intracellular Ca2+ in regulation of basal ileal Na and Cl transport but not in cAMP-induced secretion. There appear to be several pools of intracellular Ca2+ involved in neurohumoral effects on active electrolyte transport.

The concentration-dependence of CRF-like diuretic peptide: mechanisms of action.

1998 ◽  
Vol 201 (11) ◽  
pp. 1753-1762 ◽  
Author(s):  
T M Clark ◽  
T K Hayes ◽  
G M Holman ◽  
K W Beyenbach
Keyword(s):  
Short Circuit ◽  
Second Messenger ◽  
Short Circuit Current ◽  
Paracellular Pathway ◽  
Ionophore A23187 ◽  
Na Transport ◽  
Principal Mechanism ◽  
Cl Transport ◽  
Mediated Effects ◽  
Stimulation Of

The mechanism of action of synthetic CCRF-DP, the corticotropin-releasing factor (CRF)-related diuretic peptide of the salt marsh mosquito Culex salinarius, was investigated in isolated Malpighian tubules of the yellow fever mosquito Aedes aegypti. A low concentration of CCRF-DP (10(-9)mol l-1) caused a small but insignificant increase in transepithelial secretion of NaCl and fluid, but significantly reduced transepithelial voltage and resistance without a change in short-circuit current, pointing to the stimulation of passive Cl- transport through the paracellular pathway as the principal mechanism of a mild diuresis. Significant changes in voltage and resistance but not in short-circuit current were duplicated by the ionophore A23187 (0.4 micromol l-1), suggesting Ca2+ as a second messenger at 10(-9)mol l-1 CCRF-DP. A high concentration of CCRF-DP (10(-7)mol l-1) significantly increased transepithelial secretion of NaCl and fluid and significantly increased short-circuit current, pointing to the stimulation of active Na+ transport through the transcellular pathway as the mechanism of a strong diuresis. This effect was mimicked by dibutyryl-cAMP, suggesting cAMP as a second messenger at 10(-7)mol l-1 CCRF-DP. Dibutyryl-cGMP had no effects. These results suggest dose-dependent, receptor-mediated effects of CCRF-DP that target discrete transport pathways via discrete second messengers: low concentrations of CCRF-DP cause a mild diuresis, apparently via Ca2+-mediated effects on paracellular Cl- transport, and high concentrations cause a strong diuresis via cAMP-mediated effects on active transcellular Na+ transport in addition to the effects on the paracellular pathway.

Brush-border tyrosine phosphorylation stimulates ileal neutral NaCl absorption and brush-border Na(+)-H+ exchange

1994 ◽  
Vol 266 (4) ◽  
pp. G647-G656 ◽  
Author(s):  
M. Donowitz ◽  
J. L. Montgomery ◽  
M. S. Walker ◽  
M. E. Cohen
Keyword(s):  
Brush Border ◽  
Kinase Inhibitor ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Short Circuit Current ◽  
Intestinal Epithelial ◽  
Rabbit Ileum ◽  
Nacl Absorption ◽  
A 23187 ◽  
Dependent Inhibition

The drug genistein, a tyrosine (Tyr) kinase inhibitor, was used to define a role for Tyr phosphorylation in regulation of basal and stimulated neutral NaCl absorption in rabbit ileum. Brush-border vesicles contain Tyr-phosphorylated peptides. Genistein freeze-thawed into the vesicles caused a concentration-dependent inhibition of at least three peptides with M(r) 111,000, 83,000, and 80,000. Studied with the Ussing chamber-voltage clamp technique, genistein added to the ileal mucosal surface inhibited neutral NaCl absorption. Direct addition of genistein to brush-border vesicles made from ileal villus cells inhibited brush-border Na(+)-H+ exchange but not D-glucose-stimulated Na+ uptake. These effects were not duplicated by genistin, a drug with similar structure to genistein but lacking Tyr kinase inhibiting properties. Serosal but not mucosal epidermal growth factor (EGF) stimulated NaCl absorption. Mucosal genistein but not genistin also altered second-messenger regulation of neutral NaCl absorption, inhibiting the effect of Ca2+ ionophore A-23187 and of serosal EGF but not affecting the transport changes caused by 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP). In contrast, the Cl secretory effects indicated by the increase in short-circuit current for all three agents, A-23187, EGF, and 8-BrcAMP, were inhibited by mucosal genistein. These results suggest that 1) a Tyr kinase is involved in basally stimulating ileal neutral NaCl absorption and brush-border Na(+)-H+ exchange; 2) EGF stimulates NaCl absorption by an effect exerted from the serosal surface, but the effect also involves a brush-border Tyr kinase; 3) brush-border Tyr kinase is involved in the ability of Ca2+ ionophore A-23187 to inhibit neutral NaCl absorption but is not involved in the transport effects of cAMP. This study suggests that Tyr kinase(s) acting over short time periods is involved in stimulation of neutral NaCl absorption and brush-border Na(+)-H+ exchange and also in Ca(2+)-induced inhibition of NaCl absorption. These studies represent the first example of a brush-border Tyr kinase being involved in short-term signal transduction in intestinal epithelial cells.

Norepinephrine induces Na+-H+ and Cl -HCO3 exchange in Amphiuma intestine: locus and response to amiloride

1988 ◽  
Vol 255 (1) ◽  
pp. G18-G26
Author(s):  
J. F. White ◽  
C. F. Hinton
Keyword(s):  
Small Intestine ◽  
Acid Secretion ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Induced Current ◽  
Free Medium ◽  
Cl Transport ◽  
Transepithelial Voltage ◽  
Unidirectional Fluxes ◽  
Stimulation Of

Catecholamines stimulate Na+-dependent acid secretion by Amphiuma small intestine. Studies were undertaken to localize the response within the mucosa and characterize the effect on Na+ and Cl- transport. Stripped segments of jejunum were mounted in tissue chambers that permitted isolation of villus or intervillus epithelium. In Cl-free medium, norepinephrine (NE) stimulated the transepithelial voltage (Vms) in both villus and intervillus epithelium, whereas galactose and valine elevated Vms predominately in the villus. Paired segments of whole mucosa were maintained under short circuit while the rate of acid secretion (JH) was measured by titration of the unbuffered serosal medium and unidirectional fluxes of Na+ were measured by 22Na. NE significantly stimulated net Na+ absorption (JNanet), short circuit current (Isc), and JH. Amiloride reduced JH and Isc in NE-stimulated tissues and blocked the stimulation of JNanet by NE. The NE-induced current was nearly completely and reversibly inhibited by replacement of luminal medium HCO3- or CO2. NE significantly stimulated net Cl- absorption without changing Isc or JH. It is concluded that cells throughout the mucosa respond to catecholamines with enhanced Na+ and Cl- absorption, possibly through induction or stimulation of Na+-H+ and Cl- -HCO3- exchange.

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