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Populations of interstitial cells of Cajal (ICC) are altered in several gastrointestinal neuromuscular disorders. ICC are identified typically by ultrastructure and expression of Kit (CD117), a protein that is also expressed on mast cells. No other molecular marker currently exists to independently identify ICC. The expression of ANO1 (DOG1, TMEM16A), a Ca2+-activated Cl- channel, in gastrointestinal stromal tumors suggests it may be useful as an ICC marker. The aims of this study were therefore to determine the distribution of Ano1 immunoreactivity compared with Kit and to establish whether Ano1 is a reliable marker for human and mouse ICC. Expression of Ano1 in human and mouse stomach, small intestine, and colon was investigated by immunofluorescence labeling using antibodies to Ano1 alone and in combination with antibodies to Kit. Colocalization of immunoreactivity was demonstrated by epifluorescence and confocal microscopy. In the muscularis propria, Ano1 immunoreactivity was restricted to cells with the morphology and distribution of ICC. All Ano1-positive cells in the muscularis propria were also Kit positive. Kit-expressing mast cells were not Ano1 positive. Some non-ICC in the mucosa and submucosa of human tissues were Anol positive but Kit negative. A few (3.2%) Ano1-positive cells in the human gastric muscularis propria were labeled weakly for Kit. Ano1 labels all classes of ICC and represents a highly specific marker for studying the distribution of ICC in mouse and human tissues with an advantage over Kit since it does not label mast cells. [ABSTRACT FROM AUTHOR]

During acute exacerbations of inflammatory bowel diseases, oxidants are generated through the interactions of bacteria in the lumen, activated granulocytes, and cells of the colon mucosa. In this study we explored the ability of one such class of oxidants, represented by monochloramine (NH2CI), to serve as agonists of Ca2+ and Zn2+ accumulation within the colonocyte. Individual colon crypts prepared from Sprague-Dawley rats were mounted in perfusion chambers after loading with fluorescent reporters fura 2-AM and fluozin 3-AM. These reporters were characterized, in situ, for responsiveness to Ca2+ and Zn2+ in the cytoplasm. Responses to different concentrations of NH2Cl (50, 100, and 200 µM) were monitored. Subsequent studies were designed to identify the sources and mechanisms of NH2Cl-induced increases in Ca2+ and Zn2+ in the cytoplasm. Exposure to NH2CI led to dose-dependent increases in intracellular Ca2+ concentration ([Ca2+]i) in the range of 200-400 nM above baseline levels. Further studies indicated that NH2CI-induced accumulation of Ca2+ in the cytoplasm is the result of release from intracellular stores and basolateral entry of extracellular Ca2+ through store-operated channels. In addition, exposure to NH2CI resulted in dose-dependent and sustained increases in intracellular Zn2+ concentration ([Zn2+]i) in the nanomolar range. These alterations were neutralized by dithiothreitol, which shields intracellular thiol groups from oxidation. We conclude that Ca2+- and Zn2+-handling proteins are susceptible to oxidation by chloramines, leading to sustained, but not necessarily toxic, increases in [Ca2+]i and [Zn2+]i. Under certain conditions, NH2CI may act not as a toxin but as an agent that activates intracellular signaling pathways. [ABSTRACT FROM AUTHOR]

Human jejunum smooth muscle cells (SMCs) and interstitial cells of Cajal (ICCs) express the SCN5A-encoded voltage-gated, mechanosensitive sodium channel NaV1.5. NaV1.5 contributes to small bowel excitability, and NaV1.5 inhibitor ranolazine produces constipation by an unknown mechanism. We aimed to determine the presence and molecular identity of Na(+) current in the human colon smooth muscle and to examine the effects of ranolazine on Na(+) current, mechanosensitivity, and smooth muscle contractility. Inward currents were recorded by whole cell voltage clamp from freshly dissociated human colon SMCs at rest and with shear stress. SCN5A mRNA and NaV1.5 protein were examined by RT-PCR and Western blots, respectively. Ascending human colon strip contractility was examined in a muscle bath preparation. SCN5A mRNA and NaV1.5 protein were identified in human colon circular muscle. Freshly dissociated human colon SMCs had Na(+) currents (-1.36 ± 0.36 pA/pF), shear stress increased Na(+) peaks by 17.8 ± 1.8% and accelerated the time to peak activation by 0.7 ± 0.3 ms. Ranolazine (50 μM) blocked peak Na(+) current by 43.2 ± 9.3% and inhibited shear sensitivity by 25.2 ± 3.2%. In human ascending colon strips, ranolazine decreased resting tension (31%), reduced the frequency of spontaneous events (68%), and decreased the response to smooth muscle electrical field stimulation (61%). In conclusion, SCN5A-encoded NaV1.5 is found in human colonic circular smooth muscle. Ranolazine blocks both peak amplitude and mechanosensitivity of Na(+) current in human colon SMCs and decreases contractility of human colon muscle strips. Our data provide a likely mechanistic explanation for constipation induced by ranolazine., (Copyright © 2015 the American Physiological Society.)

Background: Pouchitis may occur following ileal pouch-anal anastomosis for chronic ulcerative colitis in approximately 30% of patients., Objectives: The primary objective was to determine the efficacy of medical therapies for pouchitis (including antibiotic, probiotic, and other agents) as substantiated by data from randomized controlled trials (RCTs)., Search Strategy: A search for RCTs from 1966 to October 2009 was performed using the MEDLINE, Cochrane Library, EMBASE, Web of Science, and Scopus databases., Selection Criteria: Randomized controlled treatment or prevention trials of adult patients who underwent ileal pouch-anal anastomosis for ulcerative colitis who subsequently developed pouchitis or were at risk for pouchitis were considered for inclusion., Data Collection and Analysis: Extracted data were converted to 2X2 tables and then synthesized in to a summary statistic using the Peto odds ratio (OR) and [95% confidence intervals], or weighted mean difference (WMD), using RevMan-5 for Mac OS 10.6., Main Results: Eleven RCTs fulfilled the inclusion criteria and were included in the review. The efficacy of 10 different pharmacologic agents was assessed. For the treatment of acute pouchitis (4 RCTS, 5 agents), ciprofloxacin was more effective at inducing remission than metronidazole. Neither rifaximin nor lactobacillus GG were more effective than placebo, while budesonide enemas and metronidazole were similarly effective, for inducing remission of acute pouchitis. For the treatment and maintenance of remission of chronic pouchitis (4 RCTs, 4 agents), glutamine suppositories were not more effective than butyrate suppositories, and bismuth carbomer foam enemas were not more effective than placebo, while VSL#3 was more effective than placebo in maintaining remission of chronic pouchitis in patients with chronic pouchitis who achieved remission with antibiotics. For the prevention of pouchitis (3 RCTs, 2 agents), in one study VSL#3 was more effective than placebo while in another study VSL#3 was not more effective than no treatment. Allopurinol was not more effective than placebo, while inulin was more effective than placebo but the results were not clinically significant., Authors' Conclusions: For acute pouchitis, ciprofloxacin was more effective than metronidazole, while budesonide enemas and metronidazole were similarly effective. For chronic pouchitis, VSL#3 was more effective than placebo. For the prevention of pouchitis, VSL#3 was more effective than placebo. Larger RCTs are needed to determine the optimal agent(s) for the treatment and prevention of pouchitis.

Populations of interstitial cells of Cajal (ICC) are altered in several gastrointestinal neuromuscular disorders. ICC are identified typically by ultrastructure and expression of Kit (CD117), a protein that is also expressed on mast cells. No other molecular marker currently exists to independently identify ICC. The expression of ANO1 (DOG1, TMEM16A), a Ca(2+)-activated Cl(-) channel, in gastrointestinal stromal tumors suggests it may be useful as an ICC marker. The aims of this study were therefore to determine the distribution of Ano1 immunoreactivity compared with Kit and to establish whether Ano1 is a reliable marker for human and mouse ICC. Expression of Ano1 in human and mouse stomach, small intestine, and colon was investigated by immunofluorescence labeling using antibodies to Ano1 alone and in combination with antibodies to Kit. Colocalization of immunoreactivity was demonstrated by epifluorescence and confocal microscopy. In the muscularis propria, Ano1 immunoreactivity was restricted to cells with the morphology and distribution of ICC. All Ano1-positive cells in the muscularis propria were also Kit positive. Kit-expressing mast cells were not Ano1 positive. Some non-ICC in the mucosa and submucosa of human tissues were Ano1 positive but Kit negative. A few (3.2%) Ano1-positive cells in the human gastric muscularis propria were labeled weakly for Kit. Ano1 labels all classes of ICC and represents a highly specific marker for studying the distribution of ICC in mouse and human tissues with an advantage over Kit since it does not label mast cells.

During acute exacerbations of inflammatory bowel diseases, oxidants are generated through the interactions of bacteria in the lumen, activated granulocytes, and cells of the colon mucosa. In this study we explored the ability of one such class of oxidants, represented by monochloramine (NH(2)Cl), to serve as agonists of Ca(2+) and Zn(2+) accumulation within the colonocyte. Individual colon crypts prepared from Sprague-Dawley rats were mounted in perfusion chambers after loading with fluorescent reporters fura 2-AM and fluozin 3-AM. These reporters were characterized, in situ, for responsiveness to Ca(2+) and Zn(2+) in the cytoplasm. Responses to different concentrations of NH(2)Cl (50, 100, and 200 microM) were monitored. Subsequent studies were designed to identify the sources and mechanisms of NH(2)Cl-induced increases in Ca(2+) and Zn(2+) in the cytoplasm. Exposure to NH(2)Cl led to dose-dependent increases in intracellular Ca(2+) concentration ([Ca(2+)](i)) in the range of 200-400 nM above baseline levels. Further studies indicated that NH(2)Cl-induced accumulation of Ca(2+) in the cytoplasm is the result of release from intracellular stores and basolateral entry of extracellular Ca(2+) through store-operated channels. In addition, exposure to NH(2)Cl resulted in dose-dependent and sustained increases in intracellular Zn(2+) concentration ([Zn(2+)](i)) in the nanomolar range. These alterations were neutralized by dithiothreitol, which shields intracellular thiol groups from oxidation. We conclude that Ca(2+)- and Zn(2+)-handling proteins are susceptible to oxidation by chloramines, leading to sustained, but not necessarily toxic, increases in [Ca(2+)](i) and [Zn(2+)](i). Under certain conditions, NH(2)Cl may act not as a toxin but as an agent that activates intracellular signaling pathways.