scholarly journals Macromolecular transport across the rabbit proximal and distal colon

Gut ◽  
1999 ◽  
Vol 44 (2) ◽  
pp. 218-225 ◽  
Author(s):  
J A Hardin ◽  
M H Kimm ◽  
M Wirasinghe ◽  
D G Gall
Keyword(s):  
Nervous System ◽  
Small Intestine ◽  
Distal Colon ◽  
Distal Segment ◽  
Proximal Colon ◽  
Colonic Epithelium ◽  
Colonic Tissue ◽  
Ussing Chambers ◽  
Macromolecular Transport ◽  
Energy Dependent

BackgroundAlthough many studies have investigated macromolecular uptake in the stomach and small intestine, little is known about macromolecular uptake in the colon.AimsTo investigate the mechanisms involved in the transport of large antigenically intact macromolecules across the proximal and distal colonic epithelium in the rabbit.MethodsThe mucosal to serosal movement of bovine serum albumin (BSA) was examined in modified Ussing chambers under short circuited conditions. The mucosal surface was exposed to varying concentrations of BSA, and after a 50 minute equilibration period, the mucosal to serosal flux of immunologically intact BSA was determined by ELISA. Total BSA flux was determined by the transport of radiolabelled 125I-BSA.ResultsIntact BSA transport in proximal and distal colonic tissue showed saturable kinetics. Intact BSA transport in the proximal and distal segment was 7% and 2% of the total 125I-BSA flux respectively. Immunologically intact BSA transport in the distal segment was significantly less than that in the proximal segment. Intact BSA transport in the proximal colon was significantly reduced following treatment with sodium fluoride, colchicine, and tetrodotoxin. Cholinergic blockade had no effect on the uptake of intact BSA.ConclusionThe findings indicate that the transport of intact macromolecules across the proximal and distal large intestine is a saturable process. Further, intact BSA transport in the proximal colon is an energy dependent process that utilises microtubules and is regulated by the enteric nervous system.

scholarly journals Long range synchronization within the enteric nervous system underlies propulsion along the large intestine in mice

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Nick J. Spencer ◽  
Lee Travis ◽  
Lukasz Wiklendt ◽  
Marcello Costa ◽  
Timothy J. Hibberd ◽  
...  
Keyword(s):  
Nervous System ◽  
Smooth Muscle ◽  
Enteric Nervous System ◽  
Lymphatic Vessels ◽  
Distal Colon ◽  
Distal Region ◽  
Proximal Colon ◽  
Synchronous Firing ◽  
Electrophysiological Recordings ◽  
Intrinsic Neurons

AbstractHow the Enteric Nervous System (ENS) coordinates propulsion of content along the gastrointestinal (GI)-tract has been a major unresolved issue. We reveal a mechanism that explains how ENS activity underlies propulsion of content along the colon. We used a recently developed high-resolution video imaging approach with concurrent electrophysiological recordings from smooth muscle, during fluid propulsion. Recordings showed pulsatile firing of excitatory and inhibitory neuromuscular inputs not only in proximal colon, but also distal colon, long before the propagating contraction invades the distal region. During propulsion, wavelet analysis revealed increased coherence at ~2 Hz over large distances between the proximal and distal regions. Therefore, during propulsion, synchronous firing of descending inhibitory nerve pathways over long ranges aborally acts to suppress smooth muscle from contracting, counteracting the excitatory nerve pathways over this same region of colon. This delays muscle contraction downstream, ahead of the advancing contraction. The mechanism identified is more complex than expected and vastly different from fluid propulsion along other hollow smooth muscle organs; like lymphatic vessels, portal vein, or ureters, that evolved without intrinsic neurons.

scholarly journals (Na+ + K+)-ATPase and plasma membrane polarity of intestinal epithelial cells: presence of a brush border antigen in the distal large intestine that is immunologically related to beta subunit.

1989 ◽  
Vol 109 (3) ◽  
pp. 1057-1069 ◽  
Author(s):  
A Marxer ◽  
B Stieger ◽  
A Quaroni ◽  
M Kashgarian ◽  
H P Hauri
Keyword(s):  
Monoclonal Antibody ◽  
Small Intestine ◽  
Epithelial Cells ◽  
Brush Border ◽  
Basolateral Membrane ◽  
Apical Cell ◽  
Distal Colon ◽  
Proximal Colon ◽  
Beta Subunit ◽  
Cell Pole

The previously produced monoclonal antibody IEC 1/48 against cultured rat intestinal crypt cells (Quaroni, A., and K. J. Isselbacher. 1981. J. Natl. Cancer Inst. 67:1353-1362) was extensively characterized and found to be directed against the beta subunit of (Na+ + K+)-ATPase as assessed by immunological and enzymatic criteria. Under nondenaturing conditions the antibody precipitated the alpha-beta enzyme complex (98,000 and 48,000 Mr). This probe, together with the monoclonal antibody C 62.4 against the alpha subunit (Kashgarian, M., D. Biemesderfer, M. Caplan, and B. Forbush. 1985. Kidney Int. 28:899-913), was used to localize (Na+ + K+)-ATPase in epithelial cells along the rat intestinal tract by immunofluorescence and immunoelectron microscopy. Both antibodies exclusively labeled the basolateral membrane of small intestine and proximal colon epithelial cells. However, in the distal colon, IEC 1/48, but not C 62.4, also labeled the brush border membrane. The cross-reacting beta-subunit-like antigen on the apical cell pole was tightly associated with isolated brush borders but was apparently devoid of (Na+ + K+)-ATPase activity. Subcellular fractionation of colonocytes in conjunction with limited proteolysis and surface radioiodination of intestinal segments suggested that the cross-reacting antigen in the brush border may be very similar to the beta subunit. The results support the notion that in the small intestine and proximal colon the enzyme subunits are exclusively targeted to the basolateral membrane while in the distal colon nonassembled beta subunit or a beta-subunit-like protein is also transported to the apical cell pole.

Effect of chronic metabolic acidosis on net electrolyte transport in rat colon

1989 ◽  
Vol 256 (6) ◽  
pp. G1036-G1040 ◽  
Author(s):  
G. M. Feldman
Keyword(s):  
Metabolic Acidosis ◽  
Distal Colon ◽  
Distal Segment ◽  
Proximal Colon ◽  
Electrolyte Transport ◽  
Rat Colon ◽  
Chronic Metabolic Acidosis ◽  
In Situ Perfusion ◽  
Arterial Blood ◽  
Acute Correction

Rats fed NH4Cl (5 meq.100 g body wt-1.day-1) for one week developed chronic metabolic acidosis and had an arterial blood pH and plasma HCO3- concentration of 7.27 +2- 0.02 and 16.2 +/- 0.8 meq/l, respectively; control animals had values of 7.36 +/- 0.01 and 22.4 +/- 0.5 meq/l, respectively. Net electrolyte transport was measured in proximal and distal colonic segments by in situ perfusion. In proximal colon, chronic metabolic acidosis increased HCO3- absorption from 3.3 +/- 0.8 to 6.4 +/- 0.6 mu eq.min-1.g-1 but did not alter Na+ absorption. In distal colon, although Na+ transport was unaffected, chronic acidosis reduced HCO3- secretion from -6.9 +/- 0.8 to -4.4 +/- 0.7 mu eq.min-1.g-1 and increased voltage from -18.9 +/- 2.0 to -51.1 +/- 4.2 mV. To evaluate the dependence of these effects on altered arterial pH and HCO3- concentration, NaHCO3 was infused intravenously, raising pH and HCO3- concentration to 7.53 +/- 0.04 and 23.9 +/- 1.7 meq/l, respectively. Although acute correction of chronic metabolic acidosis reduced HCO3- absorption in proximal colon, it did not affect HCO3- secretion or voltage in the distal segment, suggesting that proximal and distal colon respond differently to chronic metabolic acidosis. These results also suggest that chronic metabolic acidosis alters the mechanisms of ion transport in distal colon.

K+ transport in isolated guinea pig colonocytes: evidence for Na(+)-independent ouabain-sensitive K+ pump

1994 ◽  
Vol 266 (6) ◽  
pp. G1083-G1089 ◽  
Author(s):  
J. R. Del Castillo ◽  
M. C. Sulbaran-Carrasco ◽  
L. Burguillos
Keyword(s):  
Small Intestine ◽  
Epithelial Cells ◽  
Guinea Pig ◽  
Distal Colon ◽  
Proximal Colon ◽  
Metabolic Inhibition ◽  
Transport Mechanisms ◽  
Transport Pathway ◽  
K Transport

K+ transport mechanisms in epithelial cells isolated from guinea pig distal colon have been studied using 86Rb as a tracer. A transport pathway has been identified that is proposed to be identical to the mechanism mediating transepithelial K+ absorption. Guinea pig colonocytes take up K+ through at least three separate mechanisms: 1) a Na(+)-dependent, ouabain-sensitive influx that is consistent with the Na(+)-K+ pump, 2) a Na(+)-dependent bumetanide-sensitive influx consistent with the Na(+)-K(+)-2Cl- cotransporter, and 3) a Na(+)-independent ouabain-sensitive influx, consistent with an apical colonic K+ pump. These transport mechanisms are sensitive to metabolic inhibition by rotenone and to vanadate, a blocker of type P adenosinetriphosphatase (ATPases). SCH-28080, an inhibitor of gastric K(+)-H(+)-ATPase, was without effect. Measurements of net K+ fluxes revealed that isolated colonocytes concentrated K+ by two processes: 1) a Na(+)-dependent ouabain-sensitive mechanism, which is compatible with the Na(+)-K+ pump and 2) a Na(+)-independent ouabain-sensitive mechanism consistent with the proposed absorptive K+ pump. These concentrative mechanisms were also inhibited by rotenone and vanadate, but not by SCH-28080. The Na(+)-independent ouabain-sensitive K+ pump was present in the distal colon, but absent in the proximal colon and the small intestine of guinea pig. It is proposed that this Na(+)-independent ouabain-sensitive K+ pump mediates K+ absorption and is related to the luminal K(+)-ATPase.

scholarly journals Studies of mucus in mouse stomach, small intestine, and colon. I. Gastrointestinal mucus layers have different properties depending on location as well as over the Peyer's patches

2013 ◽  
Vol 305 (5) ◽  
pp. G341-G347 ◽  
Author(s):  
Anna Ermund ◽  
André Schütte ◽  
Malin E. V. Johansson ◽  
Jenny K. Gustafsson ◽  
Gunnar C. Hansson
Keyword(s):  
Small Intestine ◽  
Functional Organization ◽  
Distal Colon ◽  
Proximal Colon ◽  
Peyer's Patches ◽  
Peyer’S Patches ◽  
Mucus Layer ◽  
Adhesive Properties ◽  
Intestinal Mucus ◽  
Small Intestinal

Colon has been shown to have a two-layered mucus system where the inner layer is devoid of bacteria. However, a complete overview of the mouse gastrointestinal mucus system is lacking. We now characterize mucus release, thickness, growth over time, adhesive properties, and penetrability to fluorescent beads from stomach to distal colon. Colon displayed spontaneous mucus release and all regions released mucus in response to carbachol and PGE2, except the distal colon and domes of Peyer's patches. Stomach and colon had an inner mucus layer that was adherent to the epithelium. In contrast, the small intestine and Peyer's patches had a single mucus layer that was easily aspirated. The inner mucus layer of the distal colon was not penetrable to beads the size of bacteria and the inner layer of the proximal colon was only partly penetrable. In contrast, the inner mucus layer of stomach was fully penetrable, as was the small intestinal mucus. This suggests a functional organization of the intestinal mucus system, where the small intestine has loose and penetrable mucus that may allow easy penetration of nutrients, in contrast to the stomach, where the mucus provides physical protection, and the colon, where the mucus separates bacteria from the epithelium. This knowledge of the mucus system and its organization improves our understanding of the gastrointestinal tract physiology.

scholarly journals CD24 can be used to isolate Lgr5+ putative colonic epithelial stem cells in mice

2012 ◽  
Vol 303 (4) ◽  
pp. G443-G452 ◽  
Author(s):  
Jeffrey B. King ◽  
Richard J. von Furstenberg ◽  
Brian J. Smith ◽  
Kirk K. McNaughton ◽  
Joseph A. Galanko ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Stem Cells ◽  
Epithelial Cells ◽  
Distal Colon ◽  
Proximal Colon ◽  
Egfp Expression ◽  
Colonic Epithelium ◽  
Epithelial Stem Cells ◽  
Normal Colonic Epithelium ◽  
Crypt Base

A growing body of evidence has implicated CD24, a cell-surface protein, as a marker of colorectal cancer stem cells and target for antitumor therapy, although its presence in normal colonic epithelium has not been fully characterized. Previously, our group showed that CD24-based cell sorting can be used to isolate a fraction of murine small intestinal epithelial cells enriched in actively cycling stem cells. Similarly, we hypothesized that CD24-based isolation of colonic epithelial cells would generate a fraction enriched in actively cycling colonic epithelial stem cells (CESCs). Immunohistochemistry performed on mouse colonic tissue showed CD24 expression in the bottom half of proximal colon crypts and the crypt base in the distal colon. This pattern of distribution was similar to enhanced green fluorescent protein (EGFP) expression in Lgr5-EGFP mice. Areas expressing CD24 contained actively proliferating cells as determined by ethynyl deoxyuridine (EdU) incorporation, with a distinct difference between the proximal colon, where EdU-labeled cells were most frequent in the midcrypt, and the distal colon, where they were primarily at the crypt base. Flow cytometric analyses of single epithelial cells, identified by epithelial cell adhesion molecule (EpCAM) positivity, from mouse colon revealed an actively cycling CD24+ fraction that contained the majority of Lgr5-EGFP+ putative CESCs. Transcript analysis by quantitative RT-PCR confirmed enrichment of active CESC markers [leucine-rich-repeat-containing G protein-coupled receptor 5 (Lgr5), ephrin type B receptor 2 (EphB2), and CD166] in the CD24+EpCAM+ fraction but also showed enrichment of quiescent CESC markers [leucine-rich repeats and immunoglobin domains (Lrig), doublecortin and calmodulin kinase-like 1 (DCAMKL-1), and murine telomerase reverse transcriptase (mTert)]. We conclude that CD24-based sorting in wild-type mice isolates a colonic epithelial fraction highly enriched in actively cycling and quiescent putative CESCs. Furthermore, the presence of CD24 expression in normal colonic epithelium may have important implications for the use of anti-CD24-based colorectal cancer therapies.

Intestinal distribution of human Na+/H+ exchanger isoforms NHE-1, NHE-2, and NHE-3 mRNA

1996 ◽  
Vol 271 (3) ◽  
pp. G483-G493 ◽  
Author(s):  
P. K. Dudeja ◽  
D. D. Rao ◽  
I. Syed ◽  
V. Joshi ◽  
R. Y. Dahdal ◽  
...  
Keyword(s):  
Small Intestine ◽  
Vertical Axis ◽  
Distal Colon ◽  
Proximal Colon ◽  
Hybridization Technique ◽  
Mrna Levels ◽  
Human Intestine ◽  
Relative Contribution ◽  
Specific Localization ◽  
Ribonuclease Protection

The identity of Na+/H+ exchanger (NHE) isoforms in the human small intestine and colon and their role in vectorial Na+ absorption are not known. The present studies were undertaken to examine the regional and vertical axis distribution of NHE-1, NHE-2, and NHE-3 mRNA in the human intestine. Ribonuclease protection assays were used to quantitate the levels of mRNA of these isoforms in various regions of the human intestine. In situ hybridization technique was used to localize NHE-2 and NHE-3 mRNA in the colon. The NHE-1 isoform message was present uniformly throughout the length of the human intestine. In contrast, mRNA levels for human NHE-2 and NHE-3 isoforms demonstrated significant regional differences. The NHE-3 abundance was found in decreasing order: ileum > jejunum > proximal colon = distal colon. The NHE-2 message level in the distal colon was significantly higher than in the proximal colon but was evenly distributed in the small intestine. In addition, NHE-2 mRNA was present in surface epithelial cells as well as in cells of the crypt region, suggesting the presence of NHE-2 message throughout the vertical axis of the colonic crypts. In contrast, NHE-3 mRNA was localized to surface colonocytes in the proximal colon. On the basis of this tissue-specific localization of NHE-2 and NHE-3 mRNA, it can be speculated that the relative contribution of NHE-2 and NHE-3 isoforms in Na+ absorption in the human intestine may be region specific, and these putative apical isoforms may be differentially regulated.

Digestive Physiology of the Ground Cuscus (Phalanger gymnotis), a New Guinean Phalangerid Marsupial

1997 ◽  
Vol 45 (6) ◽  
pp. 561 ◽  
Author(s):  
I. D. Hume ◽  
M. J. Runcie ◽  
J. M. Caton
Keyword(s):  
Small Intestine ◽  
Nitrogen Concentration ◽  
Distal Colon ◽  
Short Chain Fatty Acids ◽  
Proximal Colon ◽  
Brushtail Possum ◽  
Daily Production ◽  
Natural Diet ◽  
Digestible Energy ◽  
And Function

Digestive-tract morphology and function were studied in the ground cuscus (Phalanger gymnotis), reported to be the most frugivorous of eight species of New Guinean phalangerid marsupials. When offered a mixed diet of fruit and foliage, captive animals selected a diet of more than 90% fruit. Fibre digestibility was low and variable, but apparent digestibilities of both dry matter (90%) and energy (87%) were high, and intake of digestible energy was similar to that of the Australian phalangerid Trichosurus vulpecula (common brushtail possum) in captivity. The small intestine of P. gymnotis was the longest and heaviest region of the gastrointestinal tract, but the stomach contained more digesta. The total nitrogen content of digesta was low in the stomach and small intestine, but increased four-fold in the hindgut, because of microbial activity. No difference in nitrogen concentration or in the proportions of small or medium particles was found along the hindgut, but the caecum contained a smaller proportion of large particles than the distal colon. The transit time of a large particle marker was much longer than that of a solute marker, but mean retention times (MRTs) of the two markers did not differ. Both transit times and MRTs were long relative to those reported in T. vulpecula. Although fermentation rates in the caecum and proximal colon were similar to those in T. vulpecula on a foliage diet, fluid volumes were less than one-third those of T. vulpecula, and, consequently, daily production of short-chain fatty acids (SCFAs) was less than half that in T. vulpecula, and contributed only 5% of digestible energy intake (v. 15% in T. vulpecula). These results are consistent with reports that the natural diet of P. gymnotis is based largely on fruit rather than on foliage.

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.

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