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Nickerson AJ, Rajendran VM. Dietary Na + depletion up-regulates NKCC1 expression and enhances electrogenic Cl - secretion in rat proximal colon. Cell Mol Life Sci 2023; 80:209. [PMID: 37458846 PMCID: PMC11073443 DOI: 10.1007/s00018-023-04857-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 06/25/2023] [Accepted: 07/04/2023] [Indexed: 07/20/2023]
Abstract
The corticosteroid hormone, aldosterone, markedly enhances K+ secretion throughout the colon, a mechanism critical to its role in maintaining overall K+ balance. Previous studies demonstrated that basolateral NKCC1 was up-regulated by aldosterone in the distal colon specifically to support K+ secretion-which is distinct from the more well-established role of NKCC1 in supporting luminal Cl- secretion. However, considerable segmental variability exists between proximal and distal colonic ion transport processes, especially concerning their regulation by aldosterone. Furthermore, delineating such region-specific effects has important implications for the management of various gastrointestinal pathologies. Experiments were therefore designed to determine whether aldosterone similarly up-regulates NKCC1 in the proximal colon to support K+ secretion. Using dietary Na+ depletion as a model of secondary hyperaldosteronism in rats, we found that proximal colon NKCC1 expression was indeed enhanced in Na+-depleted (i.e., hyperaldosteronemic) rats. Surprisingly, electrogenic K+ secretion was not detectable by short-circuit current (ISC) measurements in response to either basolateral bumetanide (NKCC1 inhibitor) or luminal Ba2+ (non-selective K+ channel blocker), despite enhanced K+ secretion in Na+-depleted rats, as measured by 86Rb+ fluxes. Expression of BK and IK channels was also found to be unaltered by dietary Na+ depletion. However, bumetanide-sensitive basal and agonist-stimulated Cl- secretion (ISC) were significantly enhanced by Na+ depletion, as was CFTR Cl- channel expression. These data suggest that NKCC1-dependent secretory pathways are differentially regulated by aldosterone in proximal and distal colon. Development of therapeutic strategies in treating pathologies related to aberrant colonic K+/Cl- transport-such as pseudo-obstruction or ulcerative colitis-may benefit from these findings.
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Affiliation(s)
- Andrew J Nickerson
- Departments of Physiology, Pharmacology and Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
- Departments of Biochemistry and Molecular Medicine, West Virginia University School of Medicine, 1 Medical Center Drive, Morgantown, WV, 26506, USA
- University of Pittsburgh, S929 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA, USA
| | - Vazhaikkurichi M Rajendran
- Departments of Biochemistry and Molecular Medicine, West Virginia University School of Medicine, 1 Medical Center Drive, Morgantown, WV, 26506, USA.
- Department of Medicine, West Virginia University School of Medicine, Morgantown, WV, USA.
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2
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Hempstock W, Nagata N, Ishizuka N, Hayashi H. The effect of claudin-15 deletion on cationic selectivity and transport in paracellular pathways of the cecum and large intestine. Sci Rep 2023; 13:6799. [PMID: 37100833 PMCID: PMC10133298 DOI: 10.1038/s41598-023-33431-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/12/2023] [Indexed: 04/28/2023] Open
Abstract
The large intestine plays a pivotal role in water and electrolyte balance. Paracellular transport may play a role in ion transport mechanisms in the cecum and large intestine; however, these molecular mechanisms and their physiological roles have not been fully studied. Claudin-15 forms a cation channel in tight junctions in the small intestine, but its role in the cecum and large intestine has not been investigated. This study aimed to explore the physiological role of claudin-15 in the cecum and large intestine using claudin-15 (Cldn15) KO mice. Electrical conductance, short-circuit current, Na+ flux, and dilution potential were assessed in isolated tissue preparations mounted in Ussing chambers. The induced short-circuit current of short-chain fatty acids, which are fermentative products in the intestinal tract, was also measured. Compared to wild type mice, the electrical conductance and paracellular Na+ flux was decreased in the cecum, but not the middle large intestine, while in both the cecum and the middle large intestine, paracellular Na+ permeability was decreased in Cldn15 KO mice. These results suggest that claudin-15 is responsible for Na+ permeability in the tight junctions of the cecum and large intestine and decreased Na+ permeability in the cecum may cause impaired absorption function.
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Affiliation(s)
- Wendy Hempstock
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, Shizuoka, 422-8526, Japan
- Department of Nursing, School of Nursing, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Nozomi Nagata
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, Shizuoka, 422-8526, Japan
| | - Noriko Ishizuka
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, Shizuoka, 422-8526, Japan
| | - Hisayoshi Hayashi
- Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, Shizuoka, 422-8526, Japan.
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3
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Salari A, Zhou K, Nikolovska K, Seidler U, Amiri M. Human Colonoid-Myofibroblast Coculture for Study of Apical Na +/H + Exchangers of the Lower Cryptal Neck Region. Int J Mol Sci 2023; 24:ijms24054266. [PMID: 36901695 PMCID: PMC10001859 DOI: 10.3390/ijms24054266] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 02/17/2023] [Accepted: 02/18/2023] [Indexed: 02/25/2023] Open
Abstract
Cation and anion transport in the colonocyte apical membrane is highly spatially organized along the cryptal axis. Because of lack of experimental accessibility, information about the functionality of ion transporters in the colonocyte apical membrane in the lower part of the crypt is scarce. The aim of this study was to establish an in vitro model of the colonic lower crypt compartment, which expresses the transit amplifying/progenitor (TA/PE) cells, with accessibility of the apical membrane for functional study of lower crypt-expressed Na+/H+ exchangers (NHEs). Colonic crypts and myofibroblasts were isolated from human transverse colonic biopsies, expanded as three-dimensional (3D) colonoids and myofibroblast monolayers, and characterized. Filter-grown colonic myofibroblast-colonic epithelial cell (CM-CE) cocultures (myofibroblasts on the bottom of the transwell and colonocytes on the filter) were established. The expression pattern for ion transport/junctional/stem cell markers of the CM-CE monolayers was compared with that of nondifferentiated (EM) and differentiated (DM) colonoid monolayers. Fluorometric pHi measurements were performed to characterize apical NHEs. CM-CE cocultures displayed a rapid increase in transepithelial electrical resistance (TEER), paralleled by downregulation of claudin-2. They maintained proliferative activity and an expression pattern resembling TA/PE cells. The CM-CE monolayers displayed high apical Na+/H+ exchange activity, mediated to >80% by NHE2. Human colonoid-myofibroblast cocultures allow the study of ion transporters that are expressed in the apical membrane of the nondifferentiated colonocytes of the cryptal neck region. The NHE2 isoform is the predominant apical Na+/H+ exchanger in this epithelial compartment.
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Affiliation(s)
- Azam Salari
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
| | - Kunyan Zhou
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
- Department of Thyroid Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310027, China
| | - Katerina Nikolovska
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
- Correspondence: (U.S.); (M.A.); Tel.: +49-511-532-9427 (U.S.); Fax: +49-511-532-8428 (U.S.)
| | - Mahdi Amiri
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
- Correspondence: (U.S.); (M.A.); Tel.: +49-511-532-9427 (U.S.); Fax: +49-511-532-8428 (U.S.)
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4
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Stephens CE, Whittamore JM, Hatch M. The role of NHE3 (Slc9a3) in oxalate and sodium transport by mouse intestine and regulation by cAMP. Physiol Rep 2021; 9:e14828. [PMID: 33904662 PMCID: PMC8077127 DOI: 10.14814/phy2.14828] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/01/2021] [Accepted: 03/09/2021] [Indexed: 12/14/2022] Open
Abstract
Intestinal oxalate transport involves Cl−/HCO3− exchangers but how this transport is regulated is not currently known. NHE3 (Slc9a3), an apical Na+/H+ exchanger, is an established target for regulation of electroneutral NaCl absorption working in concert with Cl−/HCO3− exchangers. To test whether NHE3 could be involved in regulation of intestinal oxalate transport and renal oxalate handling we compared urinary oxalate excretion rates and intestinal transepithelial fluxes of 14C‐oxalate and 22Na+ between NHE3 KO and wild‐type (WT) mice. NHE3 KO kidneys had lower creatinine clearance suggesting reduced GFR, but urinary oxalate excretion rates (µmol/24 h) were similar compared to the WT but doubled when expressed as a ratio of creatinine. Intestinal transepithelial fluxes of 14C‐oxalate and 22Na+ were measured in the distal ileum, cecum, and distal colon. The absence of NHE3 did not affect basal net transport rates of oxalate or sodium across any intestinal section examined. Stimulation of intracellular cAMP with forskolin (FSK) and 3‐isobutyl‐1‐methylxanthine (IBMX) led to an increase in net oxalate secretion in the WT distal ileum and cecum and inhibition of sodium absorption in the cecum and distal colon. In NHE3 KO cecum, cAMP stimulation of oxalate secretion was impaired suggesting the possibility of a role for NHE3 in this process. Although, there is little evidence for a role of NHE3 in basal intestinal oxalate fluxes, NHE3 may be important for cAMP stimulation of oxalate in the cecum and for renal handling of oxalate.
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Affiliation(s)
- Christine E Stephens
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Jonathan M Whittamore
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Marguerite Hatch
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
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5
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Hayashi H, Nagai H, Ohba KI, Soleimani M, Suzuki Y. Segmental differences in Slc26a3-dependent Cl - absorption and HCO 3- secretion in the mouse large intestine in vitro in Ussing chambers. J Physiol Sci 2021; 71:5. [PMID: 33514305 PMCID: PMC10717946 DOI: 10.1186/s12576-020-00784-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 11/19/2020] [Indexed: 12/12/2022]
Abstract
The anion exchanger slc26a3 (DRA), which is mutated in congenital chloride-losing diarrhea, is expressed in the apical membrane of the cecum and middle-distal colon but not in the proximal colon of rodent large intestines. To elucidate the functional roles of DRA, we measured unidirectional 36Cl- and 22Na+ fluxes and HCO3- secretion in vitro in each of these segments using DRA-KO mice. Robust Cl- absorption, which was largely abolished after DRA deficiency, was present in the cecum and middle-distal colon but absent in the proximal colon. Na+ absorption was present in all three segments in both the control and DRA-KO mice. The luminal-Cl--dependent HCO3- secretions in the cecum and middle-distal colon were abolished in the DRA-KO mice. In conclusion, DRA mediates Cl- absorption and HCO3- secretion in the mouse cecum and middle-distal colon, and may have roles in H2O absorption and luminal acid/base regulation in these segments.
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Affiliation(s)
- Hisayoshi Hayashi
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Hiroki Nagai
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Kou-Ichiro Ohba
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Manoocher Soleimani
- Department of Medicine, University of Cincinnati, Cincinnati, OH, 45267, USA
| | - Yuichi Suzuki
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
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6
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The anion exchanger PAT-1 (Slc26a6) does not participate in oxalate or chloride transport by mouse large intestine. Pflugers Arch 2020; 473:95-106. [PMID: 33205229 DOI: 10.1007/s00424-020-02495-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 10/23/2020] [Accepted: 11/10/2020] [Indexed: 01/20/2023]
Abstract
The membrane-bound transport proteins responsible for oxalate secretion across the large intestine remain unidentified. The apical chloride/bicarbonate (Cl-/HCO3-) exchanger encoded by Slc26a6, known as PAT-1 (putative anion transporter 1), is a potential candidate. In the small intestine, PAT-1 makes a major contribution to oxalate secretion but whether this role extends into the large intestine has not been directly tested. Using the PAT-1 knockout (KO) mouse, we compared the unidirectional absorptive ([Formula: see text]) and secretory ([Formula: see text]) flux of oxalate and Cl- across cecum, proximal colon, and distal colon from wild-type (WT) and KO mice in vitro. We also utilized the non-specific inhibitor DIDS (4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid) to confirm a role for PAT-1 in WT large intestine and (in KO tissues) highlight any other apical anion exchangers involved. Under symmetrical, short-circuit conditions the cecum and proximal colon did not transport oxalate on a net basis, whereas the distal colon supported net secretion. We found no evidence for the participation of PAT-1, or indeed any other DIDS-sensitive transport mechanism, in oxalate or Cl- by the large intestine. Most unexpectedly, mucosal DIDS concurrently stimulated [Formula: see text] and [Formula: see text] by 25-68% across each segment without impacting net transport. For the colon, these changes were directly proportional to increased transepithelial conductance suggesting this response was the result of bidirectional paracellular flux. In conclusion, PAT-1 does not contribute to oxalate or Cl- transport by the large intestine, and we urge caution when using DIDS with mouse colonic epithelium.
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Rehman S, Narayanan K, Nickerson AJ, Coon SD, Hoque KM, Sandle GI, Rajendran VM. Parallel intermediate conductance K + and Cl - channel activity mediates electroneutral K + exit across basolateral membranes in rat distal colon. Am J Physiol Gastrointest Liver Physiol 2020; 319:G142-G150. [PMID: 32567323 PMCID: PMC7500264 DOI: 10.1152/ajpgi.00011.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Transepithelial K+ absorption requires apical K+ uptake and basolateral K+ exit. In the colon, apical H+-K+-ATPase mediates cellular K+ uptake, and it has been suggested that electroneutral basolateral K+ exit reflects K+-Cl- cotransporter-1 (KCC1) operating in parallel with K+ and Cl- channels. The present study was designed to identify basolateral transporter(s) responsible for K+ exit in rat distal colon. Active K+ absorption was determined by measuring 86Rb+ (K+ surrogate) fluxes across colonic epithelia under voltage-clamp conditions. With zero Cl- in the mucosal solution, net K+ absorption was reduced by 38%, indicating that K+ absorption was partially Cl--dependent. Serosal addition of DIOA (KCC1 inhibitor) or Ba2+ (nonspecific K+ channel blocker) inhibited net K+ absorption by 21% or 61%, respectively, suggesting that both KCC1 and K+ channels contribute to basolateral K+ exit. Clotrimazole and TRAM34 (IK channel blockers) added serosally inhibited net K+ absorption, pointing to the involvement of IK channels in basolateral K+ exit. GaTx2 (CLC2 blocker) added serosally also inhibited net K+ absorption, suggesting that CLC2-mediated Cl- exit accompanies IK channel-mediated K+ exit across the basolateral membrane. Net K+ absorption was not inhibited by serosal addition of either IbTX (BK channel blocker), apamin (SK channel blocker), chromanol 293B (KV7 channel blocker), or CFTRinh172 (CFTR blocker). Immunofluorescence studies confirmed basolateral membrane colocalization of CLC2-like proteins and Na+-K+-ATPase α-subunits. We conclude that active K+ absorption in rat distal colon involves electroneutral basolateral K+ exit, which may reflect IK and CLC2 channels operating in parallel.NEW & NOTEWORTHY This study demonstrates that during active electroneutral K+ absorption in rat distal colon, K+ exit across the basolateral membrane mainly reflects intermediate conductance K+ channels operating in conjunction with chloride channel 2, with a smaller, but significant, contribution from K+-Cl- cotransporter-1 (KCC1) activity.
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Affiliation(s)
- Shabina Rehman
- 1Departments of Biochemistry West Virginia University School of Medicine, Morgantown, West Virginia
| | - Karthikeyan Narayanan
- 1Departments of Biochemistry West Virginia University School of Medicine, Morgantown, West Virginia
| | - Andrew J. Nickerson
- 1Departments of Biochemistry West Virginia University School of Medicine, Morgantown, West Virginia,2Departments of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, West Virginia
| | - Steven D. Coon
- 3Department of Biological Sciences, Port Peck Community College, Poplar, Montana
| | - Kazi Mirajul Hoque
- 4Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Geoffrey I. Sandle
- 5Leeds Institute for Medical Research at St. James’s, St. James’s University Hospital. Leeds, United Kingdom
| | - Vazhaikkurichi M. Rajendran
- 1Departments of Biochemistry West Virginia University School of Medicine, Morgantown, West Virginia,6Departments of Medicine, West Virginia University School of Medicine, Morgantown, West Virginia
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8
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Xue H, Zhang M, Ma J, Chen T, Wang F, Tang X. Lactose-Induced Chronic Diarrhea Results From Abnormal Luminal Microbial Fermentation and Disorder of Ion Transport in the Colon. Front Physiol 2020; 11:877. [PMID: 32848839 PMCID: PMC7403511 DOI: 10.3389/fphys.2020.00877] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 06/29/2020] [Indexed: 12/12/2022] Open
Abstract
Diarrhea is one of the major abdominal symptoms in lactose-intolerant subjects. The changes in the large intestinal luminal environment and disorder of the epithelial ion transport in lactose-induced diarrhea remain unclear. The present study aimed to investigate the effect of an incremental high-lactose diet (IHLD, 30%/40%/50%) on luminal microbiota, microbiota-derived metabolite concentrations and colonic ion transport. Gut microbiota were analyzed by 16S rRNA amplicon sequencing and the concentration of SCFAs by gas chromatography, galactose, lactose and lactic acid through assay kit; Ussing chamber was performed to detect basal and stimulated ion transport; The expression and location of SCFA transporters, the Na-H exchanger 3(NHE3), cystic fibrosis transporter regulater (CFTR) and NKCC1 in the colon mucosa were analyzed by western and immunostaining. The concentrations of lactose, galactose and lactic acid of the cecal content were markedly increased (P < 0.01) and SCFA concentration was significantly decreased (P < 0.01). This was associated with depletion of the Lachnospiraceae NK4A136 group and Ruminococcaceae UCG-005 and increased relative abundance of Lactobacillus, escherichia-shigella and megamonas in the cecal microbiota. The expression of monocarboxylate transporter 1 was decreased in the colonic mucosa of the IHLD group. Low NHE3 expression and phosphorylation levels, and decreases in delta basal short circuit current after apical Na+ removal in the colonic mucosa of the IHLD group contributed to Na+ accumulation in the lumen and decrease stimulated Cl– secretion with low CFTR and NKCC1 expression would compensate for water and electrolyte loss during the diarrhea process. These results indicated that the persistence of the diarrhea state was maintained by abnormal colonic microbiota fermentation leading to high concentrations of lactose, galactose and lactic acid and low SCFAs in the lumen, and decreased Na+ absorption with the low NHE3 expression and phosphorylation levels.
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Affiliation(s)
- Hong Xue
- Digestive Laboratory of Traditional Chinese Medicine Research Institute of Spleen and Stomach Diseases, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Min Zhang
- Digestive Laboratory of Traditional Chinese Medicine Research Institute of Spleen and Stomach Diseases, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jinxin Ma
- Digestive Laboratory of Traditional Chinese Medicine Research Institute of Spleen and Stomach Diseases, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Ting Chen
- Digestive Laboratory of Traditional Chinese Medicine Research Institute of Spleen and Stomach Diseases, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Fengyun Wang
- Digestive Laboratory of Traditional Chinese Medicine Research Institute of Spleen and Stomach Diseases, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Xudong Tang
- Digestive Laboratory of Traditional Chinese Medicine Research Institute of Spleen and Stomach Diseases, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
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9
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Bekusova VV, Falchuk EL, Okorokova LS, Kruglova NM, Nozdrachev AD, Markov AG. Increased paracellular permeability of tumor-adjacent areas in 1,2-dimethylhydrazine-induced colon carcinogenesis in rats. Cancer Biol Med 2018; 15:251-259. [PMID: 30197792 PMCID: PMC6121046 DOI: 10.20892/j.issn.2095-3941.2018.0016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Objective: The morphology and functions of the proximal and distal large intestine are not the same. The incidence of colorectal cancer in these regions is also different, as tumors more often appear in the descending colon than in the ascending colon. Inflammatory bowel disease and colorectal cancer can increase transepithelial permeability, which is a sign of reduced intestinal barrier function. However, there is not enough evidence to establish a connection between the difference in colorectal cancer incidence in the proximal and distal colon and intestinal permeability or the effects of carcinogenesis on the barrier properties in various areas of the colon. The aim of the study was to assess the permeability of different segments of the large intestine according to a developed mapping methodology in healthy rats and rats with 1,2-dimethylhydrazine (DMH)-induced colon adenocarcinoma. Methods: The short circuit current, the transepithelial electrical resistance and the paracellular permeability to fluorescein of large intestine wall of male Wistar rats were examined in the Ussing chambers. The optical density of the solution from the serosa side to assess the concentration of the diffused fluorescein from mucosa to serosa was analyzed by spectrophotometry. The morphometric and histological studies were performed by optical microscopy. Results: Rats with DMH-induced colon adenocarcinomas showed elevated transepithelial electrical resistance in the areas of neoplasm development. In contrast, there was no change in the electrophysiological properties of tumor adjacent areas, however, the paracellular permeability of these areas to fluorescein was increased compared to the control rats and was characterized by sharply reduced barrier function. Conclusions: The barrier properties of the colon vary depending on tumor location. The tumors were less permeable than the intact intestinal wall and probably have a negative influence on tumor-adjacent tissues by disrupting their barrier function.
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Affiliation(s)
- Viktoria V Bekusova
- Department of Physiology, St. Petersburg State University, St. Petersburg 197183, Russia
| | - Evgeny L Falchuk
- Department of Physiology, St. Petersburg State University, St. Petersburg 197183, Russia
| | - Larisa S Okorokova
- Department of Physiology, St. Petersburg State University, St. Petersburg 197183, Russia
| | - Natalia M Kruglova
- Department of Physiology, St. Petersburg State University, St. Petersburg 197183, Russia
| | - Alexander D Nozdrachev
- Department of Physiology, St. Petersburg State University, St. Petersburg 197183, Russia.,I.P.Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg 199034, Russia
| | - Alexander G Markov
- Department of Physiology, St. Petersburg State University, St. Petersburg 197183, Russia
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10
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Yildirim H, Sunay FB, Sinan S, Köçkar F. In vivo effects of curcumin on the paraoxonase, carbonic anhydrase, glucose-6-phosphate dehydrogenase and β-glucosidase enzyme activities in dextran sulphate sodium-induced ulcerative colitis mice. J Enzyme Inhib Med Chem 2016; 31:1583-90. [DOI: 10.3109/14756366.2016.1158173] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Hatice Yildirim
- Department of Molecular Biology and Genetics, Faculty of Science and Literature, Balikesir University, Balikesir, Turkey and
| | - Fatma Bahar Sunay
- Department of Histology & Embryology, Medical Faculty, Balikesir University, Balikesir, Turkey
| | - Selma Sinan
- Department of Molecular Biology and Genetics, Faculty of Science and Literature, Balikesir University, Balikesir, Turkey and
| | - Feray Köçkar
- Department of Molecular Biology and Genetics, Faculty of Science and Literature, Balikesir University, Balikesir, Turkey and
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11
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Bachmann O, Seidler U. News from the end of the gut--how the highly segmental pattern of colonic HCO₃⁻ transport relates to absorptive function and mucosal integrity. Biol Pharm Bull 2011; 34:794-802. [PMID: 21628874 DOI: 10.1248/bpb.34.794] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A number of transport mechanisms in the colonic epithelium contribute to HCO₃⁻ movement across the apical and basolateral membranes, but this ion has been largely regarded as a by-product of the transport functions it is involved in, such as NaCl or short chain fatty acid (SCFA) absorption. However, emerging data points to several specific roles of HCO₃⁻ for colonic epithelial physiology, including pH control in the colonic surface microenvironment, which is important for transport and immune functions, as well as the secretion and the rheological properties of the mucus gel. Furthermore, recent studies have demonstrated that colonic HCO₃⁻ transporters are expressed in a highly segmental as well as species-specific manner. This review summarizes recently gathered information on the functional anatomy of the colon, the roles of HCO₃⁻ in the colonic epithelium, colonic mucosal integrity, and the expression and function of HCO₃⁻ transporting mechanisms in health and disease.
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Affiliation(s)
- Oliver Bachmann
- Department of Gastroenterology, Hepatology, and Endocrinology, Hannover Medical School, Hannover, Germany
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12
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Talbot C, Lytle C. Segregation of Na/H exchanger-3 and Cl/HCO3 exchanger SLC26A3 (DRA) in rodent cecum and colon. Am J Physiol Gastrointest Liver Physiol 2010; 299:G358-67. [PMID: 20466943 DOI: 10.1152/ajpgi.00151.2010] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The colon is believed to absorb NaCl via the coupled operation of apical Na/H exchanger-3 (NHE3) and Cl/HCO(3) exchanger SLC26A3 (DRA). Efficient coupling requires that NHE3 and DRA operate in close proximity within common luminal and cytosolic microenvironments. Thus we examined whether these proteins coexist along the apical margin of surface enterocytes by quantitative immunofluorescence microscopy in consecutive colon segments from nonfasted mice and rats. The cecocolonic profiles of NHE3 and DRA expression were roughly inverse; NHE3 was highest in proximal colon (PC) and negligible in distal colon, whereas DRA was absent in early PC and highest in the late midcolon, and DRA was prominent in the cecum whereas NHE3 was not. NHE3 and DRA coexisted only in the middle third of the colon. The consequences of unpaired NHE3/DRA expression on mucosal surface (subscript MS) pH and Na(+) concentration ([Na(+)]) were assessed in nonfasted rats in situ using miniature electrodes. In the cecum, where only DRA is expressed, pH(MS) was approximately 7.5, markedly higher than underlaying stool (6.3), consistent with net HCO(3)(-) secretion. In the early PC, where NHE3 is not expressed with DRA, pH(MS) was acidic (6.2), consistent with unopposed H(+) secretion. [Na(+)](MS) was approximately 60 mM in the cecum, decreased along the PC to approximately 20 mM, and declined further to approximately 10 mM distally. Cl(-) was secreted into the PC, then reabsorbed distally. Our results suggest a model in which 1) unpaired DRA activity in the cecum maintains an alkaline mucosal surface that could neutralize fermentative H(+); 2) unpaired NHE3 activity in the early PC preserves an acidic mucosal surface that could energize short-chain fatty acid absorption; and 3) coupled NHE3/DRA activities in the midcolon allow for vigorous NaCl absorption at a neutral pH(MS).
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13
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Kolachala VL, Vijay-Kumar M, Dalmasso G, Yang D, Linden J, Wang L, Gewirtz A, Ravid K, Merlin D, Sitaraman SV. A2B adenosine receptor gene deletion attenuates murine colitis. Gastroenterology 2008; 135:861-70. [PMID: 18601927 PMCID: PMC2632861 DOI: 10.1053/j.gastro.2008.05.049] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Revised: 05/08/2008] [Accepted: 05/15/2008] [Indexed: 01/17/2023]
Abstract
BACKGROUND & AIMS The A(2B) adenosine receptor (A(2B)AR) is the predominant adenosine receptor expressed in the colonic epithelia. We have previously shown that A(2B)AR mRNA and protein levels are up-regulated during colitis. In this study, we addressed the role of the A(2B)AR in the development of murine colitis and the potential mechanism underlying its effects. METHODS Dextran sodium sulfate (DSS), 2,4,6-trinitrobenzene sulfonic acid (TNBS), and Salmonella typhimurium were used to induce colitis in A(2B)AR-null mice (A(2B)AR(-/-)). Colitis was determined using established clinical and histologic scoring. Keratinocyte-derived chemokine (KC) measurements were performed using an enzyme-linked immunosorbent assay. RESULTS Colonic inflammation induced by DSS, TNBS, or S typhimurium was attenuated in A(2B)AR(-/-) compared with their wild-type counterparts. Clinical features, histologic score, and myeloperoxidase activity were significantly decreased in A(2B)AR(-/-) mice. However, A(2B)AR(-/-) showed increased susceptibility to systemic Salmonella infection. Tissue levels of the neutrophil chemokine, KC was decreased in colitic A(2B)AR(-/-) mice. In addition, flagellin-induced KC levels were attenuated in A(2B)AR(-/-) mice. Neutrophil chemotaxis in response to exogenous interleukin-8 was preserved in A(2B)AR(-/-) mice, suggesting intact neutrophil migration in response to appropriate stimuli. CONCLUSIONS These data demonstrate, for the first time, that the A(2B)AR plays a proinflammatory role in colitis. A(2B) receptor antagonism may be an effective treatment for acute inflammatory intestinal diseases such as acute flare of inflammatory bowel disease.
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Affiliation(s)
- Vasantha L Kolachala
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | | | - Guilliume Dalmasso
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | - Dan Yang
- Departments of Biochemistry and Medicine, Boston University School of Medicine, Boston, MA 02118
| | - Joel Linden
- Department of Medicine and Cardiovascular Research Center, University of Virginia, Charlottesville, VA
| | - Lixin Wang
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | | | - Katya Ravid
- Departments of Biochemistry and Medicine, Boston University School of Medicine, Boston, MA 02118
| | - Didier Merlin
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | - Shanthi V. Sitaraman
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA,Address correspondence to: Shanthi V. Sitaraman, Division of Digestive Diseases, Room 201-F, 615, Michael Street, Whitehead Research Building, Emory University, Atlanta, GA, 30322, Phone: 404-727-2430, Fax: 404-727-5767,
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14
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Cincunegui LM, Ituarte LMI, Viera TB, Ibañez JE, Carra GE, Saldeña TA, Saravi FD. Effects of chronic hypoxia on electrogenic transport and transport-related oxygen consumption in rat distal colon. Dig Dis Sci 2008; 53:1593-600. [PMID: 17939049 DOI: 10.1007/s10620-007-0042-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2007] [Accepted: 09/26/2007] [Indexed: 12/09/2022]
Abstract
The distal colon epithelium of rats submitted to chronic hypoxia shows higher short-circuit current (Isc) which, unlike non-hypoxic rat epithelium, has an amiloride-sensitive component despite low serum aldosterone levels. Isc and oxygen consumption (QO2) were simultaneously measured in mucosae from rats submitted to 0.5 atm for 10 days and from control rats in a modified Ussing chamber. Hypoxia increased Isc but not QO2. The slope of the regression line between Isc and QO2 reduction after ouabain addition was decreased in epithelia from hypoxic rats (P = 0.03). Chloride secretion blockade reduced Isc and QO2 in both groups, while sodium channel blockade did so only in the hypoxic group. Dual blockade in hypoxic rat epithelia caused correlated (P = 0.0025) additive decreases in Isc and QO2. Presented results suggest that chronic hypoxia induces an improved coupling between QO2 and electrogenic ion transport, and electrogenic sodium absorption despite low aldosterone levels.
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Affiliation(s)
- Liliana M Cincunegui
- Area de Física Biológica, Departamento de Morfología y Fisiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Casilla de Correo 33, Mendoza 5500, Argentina
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15
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Kolachala VL, Bajaj R, Chalasani M, Sitaraman SV. Purinergic receptors in gastrointestinal inflammation. Am J Physiol Gastrointest Liver Physiol 2008; 294:G401-10. [PMID: 18063703 DOI: 10.1152/ajpgi.00454.2007] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Purinergic receptors comprise a family of transmembrane receptors that are activated by extracellular nucleosides and nucleotides. The two major classes of purinergic receptors, P1 and P2, are expressed widely in the gastrointestinal tract as well as immune cells. The purinergic receptors serve a variety of functions from acting as neurotransmitters, to autocoid and paracrine signaling, to cell activation and immune response. Nucleosides and nucleotide agonist of purinergic receptors are released by many cell types in response to specific physiological signals, and their levels are increased during inflammation. In the past decade, the advent of genetic knockout mice and the development of highly potent and selective agonists and antagonists for the purinergic receptors have significantly advanced the understanding of purinergic receptor signaling in health and inflammation. In fact, agonist/antagonists of purinergic receptors are emerging as therapeutic modalities to treat intestinal inflammation. In this article, the distribution of the purinergic receptors in the gastrointestinal tract and their physiological and pathophysiological role in intestinal inflammation will be reviewed.
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Affiliation(s)
- Vasantha L Kolachala
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA 30322, USA
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16
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Chalfoun AT, Kreydiyyeh SI. Involvement of the cytoskeleton in the effect of PGE2 on ion transport in the rat distal colon. Prostaglandins Other Lipid Mediat 2007; 85:58-64. [PMID: 18096422 DOI: 10.1016/j.prostaglandins.2007.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2007] [Revised: 08/23/2007] [Accepted: 10/26/2007] [Indexed: 10/22/2022]
Abstract
This work aimed at studying the effect of PGE2 on water and chloride absorption from the rat distal colon and at investigating the involvement of the cytoskeleton in the modulation of colonic transporters. PGE2 increased significantly net water and chloride absorption. It increased also the activity of the Na+K+-ATPase and the expression of the Na+K+2Cl- cotransporter. The increase in pump activity was ascribed to its phosphorylation by PKA or PKC when activated upon binding of PGE2 to its receptors, and was deemed responsible for the increase in Cl- absorption. Cytochalasin B (CytoB), a disrupter of microfilaments, decreased net water and chloride absorption in presence or absence of PGE2. Furthermore it down-regulated both pump and cotransporter, and lowered Na+K+-ATPase activity. It was suggested that an intact actin cytoskeleton is required for the basal and the PGE2-elicited trafficking of both transporters. On the other hand, colchicine, an inhibitor of microtubule polymerization, had no effect on the absorption of water and chloride but abrogated the stimulatory effect of PGE2. Colchicine exerted a similar effect to that of cytochlasin on the expression of both pump and cotransporter in presence or absence of PGE2 except for the basal activity of the pump which was not altered by microtubule disruption. It was concluded that both microfilament and microtubular networks are involved in the basal and PGE2-elicited increase in colonic ion absorption.
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Affiliation(s)
- Antoine T Chalfoun
- Department of Biology, Faculty of Arts & Sciences, American University of Beirut, Bliss Street, Beirut, Lebanon
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17
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Barmeyer C, Ye JH, Sidani S, Geibel J, Binder HJ, Rajendran VM. Characteristics of rat downregulated in adenoma (rDRA) expressed in HEK 293 cells. Pflugers Arch 2007; 454:441-50. [PMID: 17492310 DOI: 10.1007/s00424-007-0213-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Accepted: 01/10/2007] [Indexed: 11/30/2022]
Abstract
Studies with apical membrane vesicles have shown that two distinct and separate anion exchange processes are present in rat distal colon, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS)-sensitive CL(-)-HCO(3)(-) exchange, and DIDS-resistant Cl(-)-OH(-) exchange. These studies proposed that anion exchanger (AE)-1 isoform encodes the former as both apical membrane DIDS-sensitive CL(-)-HCO(3)(-) exchange, and AE1 specific mRNA are present only in surface cells and are downregulated in Na-depleted rats, whereas downregulated in adenoma (DRA) encodes the latter as both DIDS-resistant Cl(-)-OH(-) exchange, and DRA-specific proteins are present in apical membranes of both surface and crypt cells and are not altered in Na(+)-depleted rats. Studies were, therefore, initiated to identify the function of rat DRA (rDRA) in vitro. rDRA cDNA isolated from rat distal colon encodes a 757-amino-acid protein which has 96 and 81% homology with mDRA and hDRA, respectively. rDRA-specific mRNA expression was detectable only in specific segments of the digestive tract (duodenum, ileum, cecum, proximal colon, and distal colon) but not in the stomach, jejunum, or in the kidney, brain, heart, and lung. HEK 293 cells stably transfected with rDRA exhibited DIDS-insensitive and intracellular acid pH (pH(i) 6.5)-sensitive Cl uptake that: (1) was significantly stimulated by outward Cl(-), HCO(3)(-), isobutyrate, and possibly OH(-) gradients; (2) was saturated as a function of increasing extracellular Cl concentrations with an apparent K (m) for Cl of 2.9 +/- 0.3 mM; and (3) was inhibited competitively by extracellular oxalate but not by SO(4)(2-). A high rate of DIDS-insensitive Cl influx at pH 6.5 was also present under physiological Cl(-) concentration. Our observations that rDRA mediates DIDS-insensitive, acid pH-dependent Cl(-) uptake are consistent with prior observations that rDRA does not mediate DIDS-sensitive Cl(-)-HCO(3)(-) exchange in rat distal colon. We speculate that, in addition to mediating pH-sensitive Cl(-) uptake, rDRA may function as a modifier of other anion transport proteins.
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Affiliation(s)
- Christian Barmeyer
- Department of Internal Medicine, Yale University, P.O. Box 208019, New Haven, CT 06520, USA
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18
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Thiesson HC, Jensen BL, Bistrup C, Ottosen PD, McNeilly AD, Andrew R, Seckl J, Skøtt O. Renal sodium retention in cirrhotic rats depends on glucocorticoid-mediated activation of mineralocorticoid receptor due to decreased renal 11β-HSD-2 activity. Am J Physiol Regul Integr Comp Physiol 2007; 292:R625-36. [PMID: 16917017 DOI: 10.1152/ajpregu.00418.2005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Downregulation of the renal glucocorticoid-metabolizing enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD-2) during liver cirrhosis may allow activation of the mineralocorticoid receptor (MR) by glucocorticoids and contribute to sodium retention. We tested this hypothesis in male Wistar rats with decompensated liver cirrhosis and ascites 7 wk after bile duct ligation (BDL). Renal 11β-HSD-2 mRNA, protein, and activity were significantly decreased in decompensated rats. The urinary Na+/K+ ratio was reduced by 40%. Renal epithelial sodium channel (ENaC) mRNA and immunostaining were only slightly affected. Complete metabolic studies, including fecal excretion, showed that the BDL rats had avid renal sodium retention. Treatment of the BDL rats with dexamethasone suppressed endogenous glucocorticoid production, normalized total sodium balance and renal sodium excretion, and reduced ascites formation to the same degree as direct inhibition of MR with K-canrenoate. Total potassium balance was negative in the BDL rats, whereas renal potassium excretion was unchanged. In the distal colon, expression of ENaC was increased in BDL rats. Fecal potassium excretion was increased in cirrhotic rats, and this was corrected by treatment with K-canrenoate but not dexamethasone. We conclude that development of sodium retention and decompensation in cirrhotic rats is associated with downregulation of renal 11β-HSD-2 activity and inappropriate activation of renal sodium reabsorption by endogenous glucocorticoids. In addition, the overall potassium loss in the BDL model is due to increased fecal potassium excretion, which is associated with upregulation of ENaC in distal colon.
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Affiliation(s)
- Helle C Thiesson
- Department of Physiology and Pharmacology, University of Southern Denmark, Odense
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19
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Kolachala VL, Obertone TS, Wang L, Merlin D, Sitaraman SV. Adenosine 2b receptor (A2bR) signals through adenylate cyclase (AC) 6 isoform in the intestinal epithelial cells. Biochim Biophys Acta Gen Subj 2006; 1760:1102-8. [PMID: 16631311 DOI: 10.1016/j.bbagen.2006.03.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Revised: 03/06/2006] [Accepted: 03/09/2006] [Indexed: 11/29/2022]
Abstract
Adenosine 2b receptor (A2bR), a G-protein coupled receptor positively coupled to adenylate cyclase, mediates key events such as chloride, IL-6 and fibronectin secretion in intestinal epithelial cells and is upregulated during intestinal inflammation. In order to gain insight into the overall mechanism of A2bR activation, in this study, we sought to characterize the AC isoform associated with A2bR signaling. The colonic epithelial cell line T84, expressing only the A2b subtype of adenosine receptor, and Chinese hamster ovary (CHO) cells, were used in these studies. cAMP was measured by luminometric assay and AC isoform expression was determined by Western blot, RT-PCR, isoform-specific stealth RNAi and Quantigene. T84 and CHO cells express all nine known AC isoforms. In order to characterize which AC isoform(s) are associated with A2bR, we used the differential inhibition of specific AC isoforms by calcium and nitric oxide. Pretreatment of cells with carbachol or nitric oxide donors such as S-Nitroso-N-acetylpencillamine (SNAP) and PAPANANOATE inhibited A2bR mediated increase in cAMP. Further, overexpression of AC-5 or AC-6 potentiated A2bR-mediated increases in cAMP levels. Finally, transfection with AC isoform-specific RNAi demonstrated that AC-6 but not AC-5 RNAi inhibited adenosine-induced cAMP levels. Taken together, these results suggest that A2bR mediates signaling through AC-6 isoform. Since pro-inflammatory cytokines such as interferon-gamma (IFN-gamma) modulate the expression of specific AC isoforms in the intestinal epithelia, our observation may have therapeutic implications for intestinal inflammation or diarrhea wherein aA2bR is upregulated.
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Affiliation(s)
- Vasantha L Kolachala
- Division of Digestive Diseases, Department of Medicine, Emory University, Room 201-F, 615 Michael Street, Whitehead Research Building, Atlanta, GA 30322, USA
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20
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Kreydiyyeh SI, Markossian S, Hodeify RF. PGE2 exerts dose-dependent opposite effects on net water and chloride absorption from the rat colon. Prostaglandins Other Lipid Mediat 2006; 79:43-52. [PMID: 16516809 DOI: 10.1016/j.prostaglandins.2005.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2005] [Revised: 07/22/2005] [Accepted: 07/25/2005] [Indexed: 10/25/2022]
Abstract
This work investigated the effect of different doses of PGE2 on net water and Cl- absorption from the rat colon, using an in situ perfusion technique. PGE2 exerted opposite effects at different concentrations. Net water and Cl- absorption was significantly reduced at low doses with a minimum at 0.4 microg/100g BW, and significantly elevated at high doses with an observed maximal effect at 21 microg/100g BW. At low doses, PGE2 increased in superficial cells, the activity of the Na+-K+ ATPase and the protein expression of the Na+K+2Cl- cotransporter, but reduced them in crypt cells. Thus, the reduction in net water and Cl- absorption was ascribed to an increase in secretion by surface cells that masked absorptive processes. At high doses, PGE2 increased significantly the activity of the Na+-K+ ATPase in superficial cells only, and was without any effect on the protein expression of the cotransporter and the pump in both surface and crypt cells. The observed increase in net water and Cl- absorption was attributed in this case to an increase in absorptive processes with no effect on secretion.
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21
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Peña-Münzenmayer G, Catalán M, Cornejo I, Figueroa CD, Melvin JE, Niemeyer MI, Cid LP, Sepúlveda FV. Basolateral localization of native ClC-2 chloride channels in absorptive intestinal epithelial cells and basolateral sorting encoded by a CBS-2 domain di-leucine motif. J Cell Sci 2005; 118:4243-52. [PMID: 16155254 DOI: 10.1242/jcs.02525] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Cl– channel ClC-2 is expressed in transporting epithelia and has been proposed as an alternative route for Cl– efflux that might compensate for the malfunction of CFTR in cystic fibrosis. There is controversy concerning the cellular and membrane location of ClC-2, particularly in intestinal tissue. The aim of this paper is to resolve this controversy by immunolocalization studies using tissues from ClC-2 knockout animals as control, ascertaining the sorting of ClC-2 in model epithelial cells and exploring the possible molecular signals involved in ClC-2 targeting. ClC-2 was exclusively localized at the basolateral membranes of surface colonic cells or villus duodenal enterocytes. ClC-2 was sorted to the basolateral membranes in MDCK, Caco-2 and LLC-PK1-μ1B, but not in LLC-PK1-μ1A cells. Mutating a di-leucine motif (L812L813) to a di-alanine changed the basolateral targeting of ClC-2 to an apical location. The basolateral membrane localization of ClC-2 in absorptive cells of the duodenum and the colon is compatible with an absorptive function for this Cl– channel. Basolateral targeting information is contained in a di-leucine motif (L812L813) within CBS-2 domain at the C-terminus of ClC-2. It is speculated that ClC-2 also contains an apical sorting signal masked by L812L813. The proposal that CBS domains in ClC channels might behave as regulatory sites sensing intracellular signals opens an opportunity for pharmacological modulation of ClC-2 targeting.
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Abstract
The intestines play an important role in the absorption and secretion of nutrients. The colon is the final area for recapturing electrolytes and water prior to excretion, and in order to maintain this electrolyte homeostasis, a complex interaction between secretory and absorptive processes is necessary. Until recently it was thought that secretion and absorption were two distinct processes associated with either crypts or surface cells, respectively. Recently it was demonstrated that both the surface and crypt cells can perform secretory and absorptive functions and that, in fact, these functions can be going on simultaneously. This issue is important in the complexities associated with secretory diarrhea and also in attempting to develop treatment strategies for intestinal disorders. Here, we update the model of colonic secretion and absorption, discuss new issues of transporter activation, and identify some important new receptor pathways that are important modulators of the secretory and absorptive functions of the colon.
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Affiliation(s)
- John P Geibel
- Department of Surgery, Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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23
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Vidyasagar S, Rajendran VM, Binder HJ. Three distinct mechanisms of HCO3- secretion in rat distal colon. Am J Physiol Cell Physiol 2004; 287:C612-21. [PMID: 15308466 DOI: 10.1152/ajpcell.00474.2003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
HCO(3)(-) secretion has long been recognized in the mammalian colon, but it has not been well characterized. Although most studies of colonic HCO(3)(-) secretion have revealed evidence of lumen Cl(-) dependence, suggesting a role for apical membrane Cl(-)/HCO(3)(-) exchange, direct examination of HCO(3)(-) secretion in isolated crypt from rat distal colon did not identify Cl(-)-dependent HCO(3)(-) secretion but did reveal cAMP-induced, Cl(-)-independent HCO(3)(-) secretion. Studies were therefore initiated to determine the characteristics of HCO(3)(-) secretion in isolated colonic mucosa to identify HCO(3)(-) secretion in both surface and crypt cells. HCO(3)(-) secretion was measured in rat distal colonic mucosa stripped of muscular and serosal layers by using a pH stat technique. Basal HCO(3)(-) secretion (5.6 +/- 0.03 microeq.h(-1).cm(-2)) was abolished by removal of either lumen Cl(-) or bath HCO(3)(-); this Cl(-)-dependent HCO(3)(-) secretion was also inhibited by 100 microM DIDS (0.5 +/- 0.03 microeq.h(-1).cm(-2)) but not by 5-nitro-3-(3-phenylpropyl-amino)benzoic acid (NPPB), a Cl(-) channel blocker. 8-Bromo-cAMP induced Cl(-)-independent HCO(3)(-) secretion (and also inhibited Cl(-)-dependent HCO(3)(-) secretion), which was inhibited by NPPB and by glibenclamide, a CFTR blocker, but not by DIDS. Isobutyrate, a poorly metabolized short-chain fatty acid (SCFA), also induced a Cl(-)-independent, DIDS-insensitive, saturable HCO(3)(-) secretion that was not inhibited by NPPB. Three distinct HCO(3)(-) secretory mechanisms were identified: 1) Cl(-)-dependent secretion associated with apical membrane Cl(-)/HCO(3)(-) exchange, 2) cAMP-induced secretion that was a result of an apical membrane anion channel, and 3) SCFA-dependent secretion associated with an apical membrane SCFA/HCO(3)(-) exchange.
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Affiliation(s)
- Sadasivan Vidyasagar
- Dept. of Internal Medicine, Yale University, PO Box 208019, New Haven, CT 06520, USA
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Kreydiyyeh SI, Usta J, Knio K, Markossian S, Dagher S. Aniseed oil increases glucose absorption and reduces urine output in the rat. Life Sci 2004; 74:663-73. [PMID: 14623036 DOI: 10.1016/j.lfs.2003.07.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Anise (Pimpinella anisum) has been used as a traditional aromatic herb in many drinks and baked foods because of the presence of volatile oils in its fruits commonly known as seeds. Hot water extracts of the seeds have been used also in folk medicine for their diuretic and laxative effect, expectorant and anti-spasmodic action, and their ability to ease intestinal colic and flatulence. The aim of this work was to study the effect of aniseed oil on transport processes through intestinal and renal epithelia and determine its mechanism of action. The essential oils were extracted from the seeds by hydrodistillation and analyzed by gas chromatography. Aniseed oil enhanced significantly glucose absorption from the rat jejunum and increased the Na+-K+ ATPase activity in a jejunal homogenate in a dose dependent manner. The oil, however, exerted no effect on water absorption from the colon and did not alter the activity of the colonic Na+-K+ ATPase. When added to drinking water, it reduced the volume of urine produced in the rat and increased the activity of the renal Na+-K+ ATPase even at extremely low concentrations. It was concluded that aniseed oil increases glucose absorption by increasing the activity of the Na+-K+ ATPase and consequently the sodium gradient needed for the sugar transport. Its anti-diuretic effect is also mediated through a similar mechanism in the kidney whereby a stimulation of the Na+-K+ pump increases tubular sodium reabsorption and osmotic water movement. The colonic Na+-K+ ATPase was however, resistant to the oil.
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Affiliation(s)
- Sawsan Ibrahim Kreydiyyeh
- Department of Biology, Faculty of Arts and Sciences, American University of Beirut, Beirut, Lebanon.
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25
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Krishnan S, Rajendran VM, Binder HJ. Apical NHE isoforms differentially regulate butyrate-stimulated Na absorption in rat distal colon. Am J Physiol Cell Physiol 2003; 285:C1246-54. [PMID: 12878493 DOI: 10.1152/ajpcell.00598.2002] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bicarbonate and butyrate stimulate electroneutral Na absorption via apical membrane Na-H exchange (NHE) in rat distal colon. cAMP downregulates NHE-3 isoform and inhibits HCO3-dependent, but not butyrate-dependent, Na absorption. This study sought to determine whether 1) the apical membrane NHE-2 and NHE-3 isoforms differentially mediated HCO3- and butyrate-dependent Na absorption, and 2) cAMP had different effects on NHE-2 and NHE-3 isoforms. The effect of specific inhibitors of NHE-2 and NHE-3 isoforms (50 microM HOE 694 and 2 microM S3226, respectively) on unidirectional 22Na transepithelial fluxes performed across isolated mucosa from rat distal colon under voltage-clamp conditions was examined. HCO3 stimulation of Na absorption was inhibited by EIPA, a nonspecific inhibitor of all NHE isoforms, by S3226 and dibutyryl cAMP but not by HOE 694. In contrast, butyrate stimulation of Na absorption was not altered by dibutyryl cAMP and was not inhibited by HOE 694 in the absence of dibutyryl cAMP, but in the presence of dibutyryl cAMP was HOE694 sensitive. In contrast, S3226 inhibited butyrate-stimulated Na absorption in the absence of dibutyryl cAMP, but not in its presence. We conclude that 1) HCO3-stimulated Na absorption is mediated solely by NHE-3 isoform, whereas butyrate-stimulated Na absorption is mediated by either NHE-3 or NHE-2 isoform, and 2) dibutyryl cAMP selectively inhibits NHE-3 isoform but stimulates NHE-2 isoform. Dibutyryl cAMP does not inhibit butyrate-stimulated Na absorption as a result of its differential effects on NHE-2 and NHE-3 isoforms.
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Affiliation(s)
- Selvi Krishnan
- Department of Internal Medicine, Yale University, PO Box 208019, New Haven, CT 06520-8019, USA
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Walker J, Jijon HB, Churchill T, Kulka M, Madsen KL. Activation of AMP-activated protein kinase reduces cAMP-mediated epithelial chloride secretion. Am J Physiol Gastrointest Liver Physiol 2003; 285:G850-60. [PMID: 12869384 DOI: 10.1152/ajpgi.00077.2003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
AMP-activated protein kinase (AMPK) is activated in response to fluctuations in cellular energy status caused by oxidative stress. One of its targets is the cystic fibrosis transmembrane conductance regulator (CFTR), which is the predominant Cl- secretory channel in colonic tissue. The aim of this study was to determine the role of AMPK in the modulation of colonic chloride secretion under conditions of oxidative stress and chronic inflammation. Chloride secretion and AMPK activity were examined in colonic tissue from adult IL-10-deficient and wild-type 129 Sv/Ev mice in the presence and absence of pharmacological AMPK inhibitors and activators, respectively. Apical levels of CFTR were measured in brush-border membrane vesicles. Cell culture studies in human colonic T84 monolayers examined the effect of hydrogen peroxide and pharmacological activation of AMPK on forskolin-stimulated chloride secretion. Inflamed colons from IL-10-deficient mice exhibited hyporesponsiveness to forskolin stimulation in association with reductions in surface CFTR expression and increased AMPK activity. Inhibition of AMPK restored tissue responsiveness to forskolin, whereas stimulation of AMPK with 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) induced tissue hyporesponsivness in wild-type mice. T84 cells exposed to hydrogen peroxide demonstrated a time-dependent increase in AMPK activity and reduction of forskolin-stimulated chloride secretion. Inhibition of AMPK prevented the reduction in chloride secretion. Treatment of cells with the AMPK activator, AICAR, resulted in a decreased chloride secretion. In conclusion, AMPK activation is linked with reductions in cAMP-mediated epithelial chloride flux and may be a contributing factor to the hyporesponsiveness seen under conditions of chronic inflammation.
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Affiliation(s)
- John Walker
- Univ. of Alberta, 6146 Dentistry Pharmacy Bldg., Edmonton, AB, Canada T6G 2C2
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Morel E, Dublineau I, Griffiths NM. Effect of radiation on cAMP, cGMP and Ca(2+)(i) pathways and their interactions in rat distal colon. Radiat Res 2003; 160:263-72. [PMID: 12926985 DOI: 10.1667/rr3041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The secretory response implicated in the intestinal response to luminal attack is altered by radiation. The cAMP, cGMP and Ca(2+)(i) pathways leading to secretion as well as the interactions between the cAMP pathway and the cGMP or Ca(2+)(i) pathway were studied in the rat distal colon 4 days after a 9-Gy abdominal X irradiation, when modifications mainly occurred. The secretory response in Ussing chambers and cAMP and cGMP accumulation in single isolated crypts were measured. The muscarinic receptor characteristics were determined in mucosal membrane preparations. The secretory response by the cAMP pathway (stimulated by vasoactive intestinal peptide or forskolin) and the cAMP accumulation in crypts were decreased (P < 0.05) after irradiation. The weak secretory response induced by the cGMP pathway (stimulated by nitric oxide or guanylin) was unaltered by radiation, and the small amount of cGMP determined in isolated crypts from the control group became undetectable in the irradiated group. Inducible NOS was not involved in the hyporesponsiveness to VIP after irradiation (there was no effect of an iNOS inhibitor). The secretory response by the Ca(2+)(i) pathway (stimulated by carbachol) was unaffected despite a decreased number and increased affinity of muscarinic receptors. The non-additivity of VIP and carbachol co-stimulated responses was unmodified. In contrast, VIP and SNP co-stimulation showed that NO enhanced the radiation-induced hyporesponsiveness to VIP through a reduced accumulation of cAMP in crypts. This study provides further understanding of the effect of ionizing radiation on the intracellular signaling pathways.
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Affiliation(s)
- E Morel
- Institut de Radioprotection et de Sûreté Nucléaire, Département de Protection de la santé de l'Homme et de Dosimétrie, Section Autonome de Radiobiologie Appliquée à la Médecine, IRSN, Fontenay aux Roses Cedex, France
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Abstract
Bicarbonate is not freely permeable to membranes. Yet, bicarbonate must be moved across membranes, as part of CO2 metabolism and to regulate cell pH. Mammalian cells ubiquitously express bicarbonate transport proteins to facilitate the transmembrane bicarbonate flux. These bicarbonate transporters, which function by different transport mechanisms, together catalyse transmembrane bicarbonate movement. Recent advances have allowed the identification of several new bicarbonate transporter genes. Bicarbonate transporters cluster into two separate families: (i) the anion exachanger (AE) family of Cl-/HCO3- exchangers is related in sequence to the NBC family of Na+/HCO3- cotransporters and the Na(+)-dependent Cl/HCO3- exchangers and (ii) some members of the SLC26a family of sulfate transporters will also transport bicarbonate but are not related in sequence to the AE/NBC family of transporters. This review summarizes our understanding of the mammalian bicarbonate transporter superfamily.
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Affiliation(s)
- Deborah Sterling
- Department of Physiology, University of Alberta, Edmonton, Canada
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Charney AN, Alexander-Chacko J, Gummaconda R, Egnor RW. Non-catalytic role of carbonic anhydrase in rat intestinal absorption. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1573:141-8. [PMID: 12399023 DOI: 10.1016/s0304-4165(02)00370-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Carbonic anhydrase (CA) inhibition reduces NaCl absorption in rat distal ileum, a pH-sensitive, low CA activity tissue, and in distal colon, a CO(2)-sensitive, high CA activity tissue. We hypothesized that CA plays a non-catalytic role in NaCl absorption in these segments. Unidirectional fluxes of Na(+) and Cl(-), and total HCO(3)(-) generation (estimated as the sum of radiolabeled HCO(3)(-) and CO(2) produced from glucose) were measured in Ussing chambers in nominally CO(2), HCO(3)(-)-free HEPES Ringer. Measurements were made in the presence and absence of 0.1 mM methazolamide, a membrane-permeant CA inhibitor. Ringer pH reduction from 7.6 to 7.1 stimulated ileal but not colonic Na(+) and Cl(-) absorption. In the ileum, methazolamide reduced J(ms)(Na) and J(ms)(Cl) and caused net Cl(-) secretion at pH 7.6, and prevented the stimulatory effect of lowering pH. In the colon, methazolamide reduced Na(+) and Cl(-) absorption at pH 7.6. Total HCO(3)(-) generation was minimal in HEPES at pH 7.6 and 7.1 in both segments, was minimally affected by methazolamide, and did not account for the changes in Cl(-) absorption caused by pH or methazolamide. We conclude that CA plays a role in ileal and colonic NaCl absorption independent of its catalytic function.
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Affiliation(s)
- Alan N Charney
- Nephrology Section, VA Medical Center, New York University School of Medicine, 423 East 23rd Street, New York, NY 10010, USA.
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Vidyasagar S, Ramakrishna BS. Effects of butyrate on active sodium and chloride transport in rat and rabbit distal colon. J Physiol 2002; 539:163-73. [PMID: 11850510 PMCID: PMC2290116 DOI: 10.1113/jphysiol.2001.013056] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Short chain fatty acids, particularly butyrate, stimulate electroneutral NaCl absorption from the colon. Their effect in colonic epithelia lacking basal electroneutral NaCl absorption is unknown. Butyrate is also reported to inhibit active Cl- secretion in the colon. The present studies were undertaken to investigate the inter-relationships between the effects of butyrate on active Na+ and Cl- transport in the colon. Studies were carried out in rabbit distal colon (known to have predominant electrogenic Na+ absorption), rat distal colon (characterised by electroneutral Na+ absorption), and hyperaldosteronaemic rat distal colon (characterised by electrogenic Na+ absorption). The effect of cholera toxin (CT) was also noted. Potential difference, short-circuit current (I(SC)) and fluxes of Na+ and Cl- were measured in stripped mucosa under voltage-clamp conditions. Butyrate stimulated electroneutral Na+ and Cl- absorption in distal colon of normal and salt-depleted rats, and stimulated Na+ absorption in rabbit distal colon. Amiloride (10(-4) M) or CT did not inhibit this process. In rabbit distal colon, stimulation of Na+ absorption by butyrate was not dependent on the presence of Cl- in the medium. Butyrate significantly decreased conductance, decreased flux of sodium from serosa to mucosa (particularly in rabbit distal colon), and decreased I(SC). Net Cl- secretion, induced by CT, was completely inhibited by butyrate. Stimulation of Na+ absorption was independent of exposure to CT. Bumetanide reversed net Cl- secretion to net absorption, but did not alter Na+ or Cl- fluxes in tissues exposed to butyrate. Thus butyrate stimulates active Na+ absorption in colonic epithelia, with or without expression of basal Na+-H+ exchange. Independently, butyrate inhibits active Cl- secretion induced by cAMP in these epithelia.
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Affiliation(s)
- S Vidyasagar
- Department of Gastrointestinal Sciences, Christian Medical College & Hospital, Vellore 632004, India
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31
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Kunzelmann K, Mall M. Electrolyte transport in the mammalian colon: mechanisms and implications for disease. Physiol Rev 2002; 82:245-89. [PMID: 11773614 DOI: 10.1152/physrev.00026.2001] [Citation(s) in RCA: 453] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The colonic epithelium has both absorptive and secretory functions. The transport is characterized by a net absorption of NaCl, short-chain fatty acids (SCFA), and water, allowing extrusion of a feces with very little water and salt content. In addition, the epithelium does secret mucus, bicarbonate, and KCl. Polarized distribution of transport proteins in both luminal and basolateral membranes enables efficient salt transport in both directions, probably even within an individual cell. Meanwhile, most of the participating transport proteins have been identified, and their function has been studied in detail. Absorption of NaCl is a rather steady process that is controlled by steroid hormones regulating the expression of epithelial Na(+) channels (ENaC), the Na(+)-K(+)-ATPase, and additional modulating factors such as the serum- and glucocorticoid-regulated kinase SGK. Acute regulation of absorption may occur by a Na(+) feedback mechanism and the cystic fibrosis transmembrane conductance regulator (CFTR). Cl(-) secretion in the adult colon relies on luminal CFTR, which is a cAMP-regulated Cl(-) channel and a regulator of other transport proteins. As a consequence, mutations in CFTR result in both impaired Cl(-) secretion and enhanced Na(+) absorption in the colon of cystic fibrosis (CF) patients. Ca(2+)- and cAMP-activated basolateral K(+) channels support both secretion and absorption of electrolytes and work in concert with additional regulatory proteins, which determine their functional and pharmacological profile. Knowledge of the mechanisms of electrolyte transport in the colon enables the development of new strategies for the treatment of CF and secretory diarrhea. It will also lead to a better understanding of the pathophysiological events during inflammatory bowel disease and development of colonic carcinoma.
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Affiliation(s)
- Karl Kunzelmann
- Department of Physiology and Pharmacology, University of Queensland, St. Lucia, Queensland, Brisbane, Australia.
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Tsuchiya Y, Suzuki Y. The effect of cAMP on electrogenic Na(+) absorption in the rat distal colon. THE JAPANESE JOURNAL OF PHYSIOLOGY 2001; 51:435-44. [PMID: 11564280 DOI: 10.2170/jjphysiol.51.435] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Cyclic AMP is a ubiquitous second messenger produced in cells in response to extracellular stimulants. The aim of this study was to examine its role in the regulation of amiloride-sensitive electrogenic Na(+) absorption in the rat distal colon by measuring the short-circuit current (I(sc)) and (22)Na(+) fluxes in a chamber-mounted mucosal sheet. Forskolin stimulated the amiloride-inhibitable I(sc) and amiloride-inhibitable (22)Na(+) absorption. 8Br-cAMP also stimulated the amiloride-inhibitable I(sc). Furthermore, isoproterenol, acting via beta-adrenergic activation, stimulated the amiloride-inhibitable I(sc). The isoproterenol-induced increase in the amiloride-sensitive I(sc) was largely suppressed by H89, a protein kinase A inhibitor. In conclusion, cAMP can upregulate amiloride-sensitive electrogenic Na(+) absorption in the rat distal colon.
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Affiliation(s)
- Y Tsuchiya
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka, 422-8526, Japan
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Rajendran VM, Binder HJ. Characterization and molecular localization of anion transporters in colonic epithelial cells. Ann N Y Acad Sci 2001; 915:15-29. [PMID: 11193571 DOI: 10.1111/j.1749-6632.2000.tb05220.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
This study describes the identification and characterization of anion transporters in apical membrane (APM) and basolateral membrane (BLM) of rat distal colon. Cl-HCO3, Cl-OH, Cl-butyrate, and butyrate-HCO3 exchanges and Na-HCO3 cotransporter are present in rat distal epithelial cells. Cl-HCO3 exchange (1) is present only in APM from surface, but not from crypt cells; (2) is also present in BLM; and (3) of surface cell is encoded by anion exchange (AE)-1 isoform, whereas BLM Cl-HCO3 is encoded by AE2 isoform. Cl-OH exchange is present only in APM, but not in BLM from surface and crypt cells, and is responsible for regulation of cell functions (i.e., cell pH and cell volume regulation). Butyrate-HCO3 exchange (1) is also present in apical membrane vesicles (AMV) from surface, but not from crypt cells; (2) is present in BLM; and (3) is responsible for SCFA-dependent HCO3 secretion. By contrast, Cl-butyrate exchange: (1) is present in APM from both surface and crypt cells; (2) is not present in BLM; and (3) recycles butyrate by absorbing Cl. Na-HCO3 cotransport: (1) is present only in BLM; (2) is expressed predominantly in midcrypt regions; and (3) may be linked to HCO3 secretion. A mechanism for HCO3 movement across the crypt apical membrane has not as yet been identified.
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Affiliation(s)
- V M Rajendran
- Department of Internal Medicine, Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520, USA.
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Abstract
BACKGROUND & AIMS The traditional paradigm of fluid movement in the mammalian colon is that fluid absorption and secretion are present in surface and crypt cells, respectively. We have recently demonstrated Na(+)-dependent fluid absorption in isolated crypts that are devoid of neurohumoral stimulation. We now explore the mechanism of Na(+)-dependent fluid absorption in isolated rat colonic crypts. METHODS Net fluid absorption was determined using microperfusion techniques and methoxy[(3)H]inulin with ion substitutions and transport inhibitors. RESULTS Net fluid absorption was reduced but not abolished by substitution of either N-methyl-D-glucamine- Cl(-) or tetramethylammonium for Na(+) and by lumen addition of 5-ethylisopropyl amiloride, an amiloride analogue that selectively inhibits Na(+)-H(+) exchange. Net fluid absorption was also dependent on lumen Cl(-) because removal of lumen Cl(-) significantly (P < 0.001) reduced net fluid absorption. DIDS at 100 micromol/L, a concentration at which DIDS is an anion exchange inhibitor, minimally reduced net fluid absorption (P < 0.05). In contrast, either 500 micromol/L DIDS, a concentration at which DIDS is known to act as a Cl(-) channel blocker, or 10 micromol/L NPPB, a Cl(-) channel blocker, both substantially inhibited net fluid absorption (P < 0.001). Finally, both the removal of bath Cl(-) and addition of bath bumetanide, an inhibitor of Na-K-2Cl cotransport and Cl(-) secretion, resulted in a significant increase in net fluid absorption. CONCLUSIONS (1) Net Na(+)-dependent net fluid absorption in the isolated colonic crypt represents both a larger Na(+)-dependent absorptive process and a smaller secretory process; and (2) the absorptive process consists of a Na(+)-dependent, HCO(3)(-)-independent process and a Na(+)-independent, Cl(-)-dependent, HCO(3)(-)-dependent process. Fluid movement in situ represents these transport processes plus fluid secretion induced by neurohumoral stimulation.
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Affiliation(s)
- J P Geibel
- Department of Surgery, Yale University, New Haven, Connecticut, USA
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McNamara B, Winter DC, Cuffe J, Taylor C, O'Sullivan GC, Harvey BJ. Rapid activation of basolateral potassium transport in human colon by oestradiol. Br J Pharmacol 2000; 131:1373-8. [PMID: 11090109 PMCID: PMC1572471 DOI: 10.1038/sj.bjp.0703714] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2000] [Accepted: 09/18/2000] [Indexed: 11/09/2022] Open
Abstract
1. We investigated the effect of oestradiol on basolateral potassium channels in human colonic epithelium. 2. Ion transport was quantified using short circuit current (I:(sc)) measurements of samples mounted in Ussing chambers. Serosal K transport was studied using nystatin permeabilization of the apical membrane. Intracellular pH changes were quantified using spectroflouresence techniques. 3. Experiments were performed with either 10 nM or 1 microM Ca(2+) in the apical bathing solution. With 10 nM Ca(2+) in the apical bathing solution addition of oestradiol (1 nM) to the basolateral bath produced a rapid increase in current (delta I(K)=11.2+/-1.2 microA.cm(-2), n=6). This response was prevented by treatment of the serosal membrane with tolbutamide (1 microM). With 1 microM Ca(2+) in the apical bathing solution addition of oestradiol produced a rapid fall in current (delta I(K)=-12.8+/-1.4 microA.cm(-2)), this response was prevented by treatment of the basolateral membrane with tetra-pentyl-ammonium (TPeA). These responses were rapid and occurred independently of protein synthesis. 4. Inhibition of basolateral Na(+)/H(+) exchange with either amiloride or a low sodium bathing solution prevented this response. These responses were prevented by inhibition of protein kinase C (PKC) with bis-indolyl-maleimide. 5. Oestradiol (1 nM) produced a rapid intracellular alkanization (mean increase=0.11 pH units; n=6; P<0.01). 6. These results suggest that oestradiol rapidly modulates serosal K transport in human colon. These effects depend upon intact Na(+)/H(+) exchange and protein kinase C. We propose a non-classical, possibly membrane linked, mechanism for oestradiol action in human colonic epithelium.
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Affiliation(s)
- B McNamara
- Department of Clinical Neurophysiology, Box 124, Addenbrookes Hospital, Cambridge, CB2 2QQ
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Fraser GM, Blendis LM, Smirnoff P, Sikular E, Niv Y, Schwartz B. Portal hypertension induces sodium channel expression in colonocytes from the distal colon of the rat. Am J Physiol Gastrointest Liver Physiol 2000; 279:G886-92. [PMID: 11052984 DOI: 10.1152/ajpgi.2000.279.5.g886] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cellular mechanisms for Na(+) retention in portal hypertension are undefined, but epithelial Na(+) channels (ENaC) may be involved. Under high-salt diet, ENaC are absent from distal colon of rat but can be induced by mineralocorticoids such as aldosterone. Presence of rat ENaC was determined by amiloride inhibition of (22)Na(+) uptake in surface colonocytes 7 and 14 days after partial portal vein ligation (PVL) or sham surgery. At both times, uptake inhibition was significantly increased in PVL rats. Presence of mRNA transcripts, determined by RT-PCR, demonstrated that channel alpha- and gamma-subunits were similarly expressed in both groups but that beta-subunit mRNA was increased in PVL rats. This confirms that there was induction of rat ENaC and indicates that beta-subunit has a regulatory role. Urinary Na(+) was decreased for 3 days after PVL but was not different at other times, and serum aldosterone levels were elevated at 7 days, at a time when urinary Na(+) output was similar to that of sham-operated rats. We conclude that PVL leads to induction of ENaC in rat distal colon. An increase in aldosterone levels may prevent natiuresis and is probably one of several control mechanisms involved in Na(+) retention in portal hypertension.
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Affiliation(s)
- G M Fraser
- Department of Gastroenterology, Rabin Medical Center, Beilinson Campus and Sackler Faculty of Medicine, University of Tel-Aviv, Petach Tikva 49100, Israel.
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Rajendran VM, Black J, Ardito TA, Sangan P, Alper SL, Schweinfest C, Kashgarian M, Binder HJ. Regulation of DRA and AE1 in rat colon by dietary Na depletion. Am J Physiol Gastrointest Liver Physiol 2000; 279:G931-42. [PMID: 11052990 DOI: 10.1152/ajpgi.2000.279.5.g931] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Two distinct Cl/anion exchange activities (Cl/HCO(3) and Cl/OH) identified in apical membranes of rat distal colon are distributed in cell type-specific patterns. Cl/HCO(3) exchange is expressed only in surface cells, whereas Cl/OH exchange is localized in surface and crypt cells. Dietary Na depletion substantially inhibits Cl/HCO(3) but not Cl/OH exchange. We determined whether anion exchange isoforms (AE) and/or downregulated in adenoma (DRA) are expressed in and related to apical membrane anion exchanges by examining localization of AE isoform-specific and DRA mRNA expression in normal and Na-depleted rats. Amplification of AE cDNA fragments by RT-PCR with colonic mRNA as template indicates that AE1 and AE2 but not AE3 mRNAs are expressed. In situ hybridization study revealed that AE1 mRNA is expressed predominantly in surface but not crypt cells. In contrast, AE2 polypeptide is expressed in basolateral membranes and DRA protein is expressed in apical membranes of both surface and crypt cells. AE1 mRNA is only minimally present in proximal colon, and DRA mRNA abundance is similar in distal and proximal colon. Dietary Na depletion reduces AE1 mRNA abundance but did not alter DRA mRNA abundance. This indicates that AE1 encodes surface cell-specific aldosterone-regulated Cl/HCO(3) exchange, whereas DRA encodes aldosterone-insensitive Cl/OH exchange.
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Affiliation(s)
- V M Rajendran
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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Greenwood-Van Meerveld B, Tyler K, Keith JC. Recombinant human interleukin-11 modulates ion transport and mucosal inflammation in the small intestine and colon. J Transl Med 2000; 80:1269-80. [PMID: 10950118 DOI: 10.1038/labinvest.3780135] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Human recombinant interleukin 11 (rhIL-11) is a cytokine that suppresses the clinical signs of colitis in animal models of inflammatory bowel disease (IBD) and may be an effective therapeutic agent in the treatment of IBD. The objective of the current study was to investigate whether rhIL-11 was capable of reversing abnormalities in secretomotor function associated with gut inflammation. We investigated the effects of rhIL-11 on epithelial electrogenic ion transport in the jejunum and colon. Application of rhIL-11 (10 to 10,000 ng/ml) at either the luminal or serosal side of mucosal sheets isolated from control rats induced a concentration-dependent reduction of transmural potential difference (PD) in the jejunum and decreased the short-circuit current (Isc), representative of active electrogenic transport, in the colon. To investigate the effect of rhIL-11 on an inflamed gut, we isolated jejunal and colonic tissue from HLA-B27 transgenic rats with active inflammation of the bowel that represents an animal model of IBD. In jejunum and colon isolated from HLA-B27 transgenic rats, basal electrogenic ion transport was significantly attenuated and, under these conditions, rhIL-11 caused no changes in either transmural PD or Isc. However, in HLA-B27 rats, pretreatment with subcutaneous doses of rhIL-11 suppressed the symptoms of diarrhea, normalized myeloperoxidase activity in the jejunum and colon and healed mucosal injury. In the jejunum from HLA-B27 rats, healing of the intestinal inflammatory response enhanced basal transmural PD and the rhIL-11-duced changes in mucosal ion transport resembled those seen in uninflamed controls. Conversely, in the colon, healing of the mucosa did not normalize basal active ion transport nor did it reverse the inhibition of rhIL-11-induced changes in colonic Isc. Our results suggest that endogenous IL-11 may act as a modulator of epithelial transport under physiologic conditions and may act as a potent anti-inflammatory cytokine during active intestinal inflammation.
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Affiliation(s)
- B Greenwood-Van Meerveld
- Basic Science Laboratories, Oklahoma Foundation for Digestive Research, Oklahoma City 73104, USA.
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Dublineau I, Ksas B, Griffiths NM. Functional changes in the rat distal colon after whole-body irradiation: dose-response and temporal relationships. Radiat Res 2000; 154:187-95. [PMID: 10931691 DOI: 10.1667/0033-7587(2000)154[0187:fcitrd]2.0.co;2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The aim of this study was to determine the acute radiation response of the rat distal colon by in vivo and in vitro measurements of the functions of the colon over a range of radiation doses. Rats received a whole-body irradiation of 2 to 12 Gy and were studied from 1 to 7 days after exposure. In vivo water and electrolyte absorption was measured by insertion of an agarose cylinder in the colon of anesthetized rats. In vitro transepithelial electrical parameters (potential difference, short-circuit current, transepithelial conductance) were measured in Ussing chambers in basal and agonist-stimulated conditions. In vivo and in vitro functional studies were completed by standard histological analyses. The majority of functional modifications appeared at 4 days after exposure. At this time, a dose-dependent decrease in absorption of water and sodium/chloride ions in the colon was noted. In contrast, a twofold increase in potassium secretion was observed for every radiation dose studied. The response to secretagogues was attenuated at doses >8 Gy. Modifications of basal transepithelial electrical parameters together with marked histological alterations were observed at 4 days with the higher doses (>/=10 Gy). In conclusion, these results show that functions of the colon are affected by irradiation and may contribute to diarrhea induced by ionizing radiation.
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Affiliation(s)
- I Dublineau
- Institut de Protection et de Sûreté Nucléaire, Département de Protection de la santé de l'Homme et de Dosimétrie, Section Autonome de Radiobiologie Appliquée à la Médecine, IPSN, BP no. 6, F-92265 Fontenay-aux-Roses Cedex, France
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Singh SK, Binder HJ. Chapter 3 Specialized properties of colonic epithelial membranes: Apparent permeability barrier in colonic crypts. CURRENT TOPICS IN MEMBRANES 2000. [DOI: 10.1016/s1063-5823(00)50005-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Montrose MH, Kere J. Chapter 8 Anion absorption in the intestine: Anion transporters, short-chain fatty acids, and role of the DRA gene product. CURRENT TOPICS IN MEMBRANES 2000. [DOI: 10.1016/s1063-5823(00)50010-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Riegler M, Castagliuolo I, Wlk M, Pothoulakis C. Substance P causes a chloride-dependent short-circuit current response in rabbit colonic mucosa in vitro. Scand J Gastroenterol 1999; 34:1203-11. [PMID: 10636067 DOI: 10.1080/003655299750024715] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND The neuropeptide substance P (SP) induces secretion in animals. The effect of SP on rabbit colon is not known. We therefore investigated the effect of SP on rabbit colonic mucosa mounted in Ussing chambers. METHODS Colonic mucosae were incubated with SP in Cl -containing or Cl -free buffer. Drugs for pharmacologic characterization of SP-induced electrophysiologic changes were applied to the serosal bath 30 min before SP administration. RESULTS Serosal, but not luminal, administration of SP (10(-8)-10(-6) M) induced a rapid, transient, bumetanide-sensitive, dose- and chloride-dependent short-circuit current (Isc) increase (P < 0.001), which was inhibited by 85%, 80%, 82%, 90%, and 70% after serosal preincubation with the neurokinin-1 (NK-1) receptor antagonist CP-96,345, the neuronal blocker tetrodotoxin (10(-6)M), the mast cell stabilizer lodoxamide (10(-6) M), the H1-receptor antagonist pyrilamine (10(-6) M), or the prostaglandin synthesis inhibitor indomethacin (10(-6) M), respectively (P < 0.001). CONCLUSIONS SP stimulates a chloride-dependent Isc increase in the rabbit colon which is mediated by nerves and mast cells and the mast cell product histamine.
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Affiliation(s)
- M Riegler
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA
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Riegler M, Castagliuolo I, So PT, Lotz M, Wang C, Wlk M, Sogukoglu T, Cosentini E, Bischof G, Hamilton G, Teleky B, Wenzl E, Matthews JB, Pothoulakis C. Effects of substance P on human colonic mucosa in vitro. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:G1473-83. [PMID: 10362651 DOI: 10.1152/ajpgi.1999.276.6.g1473] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Previous studies indicated that the peptide substance P (SP) causes Cl--dependent secretion in animal colonic mucosa. We investigated the effects of SP in human colonic mucosa mounted in Ussing chamber. Drugs for pharmacological characterization of SP-induced responses were applied 30 min before SP. Serosal, but not luminal, administration of SP (10(-8) to 10(-6) M) induced a rapid, monophasic concentration and Cl--dependent, bumetanide-sensitive short-circuit current (Isc) increase, which was inhibited by the SP neurokinin 1 (NK1)-receptor antagonist CP-96345, the neuronal blocker TTX, the mast cell stabilizer lodoxamide, the histamine 1-receptor antagonist pyrilamine, and the PG synthesis inhibitor indomethacin. SP caused TTX- and lodoxamide-sensitive histamine release from colonic mucosa. Two-photon microscopy revealed NK1 (SP)-receptor immunoreactivity on nerve cells. The tyrosine kinase inhibitor genistein concentration dependently blocked SP-induced Isc increase without impairing forskolin- and carbachol-mediated Isc increase. We conclude that SP stimulates Cl--dependent secretion in human colon by a pathway(s) involving mucosal nerves, mast cells, and the mast cell product histamine. Our results also indicate that tyrosine kinases may be involved in this SP-induced response.
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Affiliation(s)
- M Riegler
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
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Ikuma M, Kashgarian M, Binder HJ, Rajendran VM. Differential regulation of NHE isoforms by sodium depletion in proximal and distal segments of rat colon. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:G539-49. [PMID: 9950829 DOI: 10.1152/ajpgi.1999.276.2.g539] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Dietary sodium depletion has multiple diverse effects on ion transport in the rat colon, including both the induction and inhibition of electroneutral NaCl absorption in proximal and distal colon of rat, respectively. To establish the mechanism of the differential regulation of Na+ absorption by sodium depletion, this study utilized 1) HOE-694, a dose-dependent inhibitor of Na+/H+ exchanger (NHE) isoforms, in studies of proton gradient-driven 22Na uptake (i.e., Na+/H+ exchange) by apical membrane vesicles (AMV); 2) Northern blot analyses of NHE isoform-specific mRNA abundance; and 3) Western blot analyses of NHE isoform-specific protein expression. HOE-694 inhibition studies establish that 25 microM HOE-694-sensitive (NHE2) and 25 microM HOE-694-insensitive (NHE3) Na+/H+ exchange activities are present in AMV of both proximal and distal colon of normal rats. In proximal colon, dietary sodium depletion enhanced both NHE2 and NHE3 isoform-specific Na+/H+ exchange activities, protein expression, and mRNA abundance. In contrast, in distal colon both NHE2 and NHE3 isoform-specific Na+/H+ exchange activities, protein expression, and mRNA abundance were inhibited by sodium depletion. NHE1 isoform-specific mRNA abundance in proximal or distal colon was not altered by sodium depletion. Differential effects by sodium depletion on Na+/H+ exchange in rat colon are tissue specific and isoform specific; sodium depletion both induces and inhibits apical Na+/H+ exchange at a pretranslational level.
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Affiliation(s)
- M Ikuma
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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Grotjohann I, Schulzke JD, Fromm M. Electrogenic Na+ transport in rat late distal colon by natural and synthetic glucocorticosteroids. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:G491-8. [PMID: 9950824 DOI: 10.1152/ajpgi.1999.276.2.g491] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
The potency of in vitro-added corticosteroids to stimulate electrogenic Na+ absorption (JNa, the Na+ absorptive short-circuit current blockable by 10(-4) M amiloride) was determined in rat late distal colon. JNa was determined 8 h after steroid addition from the drop in short-circuit current caused by 10(-4) M amiloride. The concentration dependency of JNa was obtained for seven corticosteroids and compared with that established for aldosterone. Apparent mineralocorticoid potencies as determined from apparent Michaelis-Menten constant (Km) values were as follows: aldosterone 1. 2 nM >> RU-28362 20 nM = deoxycorticosterone 20 nM > deoxycortisol 36 nM >/= dexamethasone 37 nM >> corticosterone 170 nM > cortisol 210 nM. These steroids exhibited Vmax values of 9-13 micromol. h-1. cm-2 and similar concentration dependencies. Hill coefficients were between 1.6 and 2.1, suggesting cooperative effects between activated receptors. We conclude that corticosteroids exhibit graded mineralocorticoid potency instead of a sharp partition into exclusive groups of mineralocorticoid and nonmineralocorticoid hormones. The low apparent Km value of RU-28362 for mineralocorticoid action and the need for high concentrations of the mineralocorticoid antagonist mespirenone to block this response indicated that JNa in a native mammalian epithelium can be mediated by the glucocorticoid receptor. Glucocorticoid receptor-specific amounts of RU-28362 in combination with mineralocorticoid receptor-specific amounts of aldosterone or of the mineralocorticoid antagonist spironolactone showed cooperative action, suggesting a heterodimeric activation of JNa by the glucocorticoid receptor and mineralocorticoid receptor.
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Affiliation(s)
- I Grotjohann
- Institut für Klinische Physiologie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, D-12200 Berlin, Germany
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Abstract
Specific targeting of drugs to the colon is recognized to have several therapeutic advantages. Drugs which are destroyed by the stomach acid and/or metabolized by pancreatic enzymes are slightly affected in the colon, and sustained colonic release of drugs can be useful in the treatment of nocturnal asthma, angina and arthritis. Treatment of colonic diseases such as ulcerative colitis, colorectal cancer and Crohn's disease is more effective with direct delivery of drugs to the affected area. Likewise, colonic delivery of vermicides and colonic diagnostic agents require smaller doses. This article is aimed at providing insight into the design considerations and evaluation of colonic drug delivery systems. For this purpose, the anatomy and physiology of the lower gastrointestinal tract are surveyed. Furthermore, the biopharmaceutical aspects are considered in relation to drug absorption in the colon and hence various approaches to colon-specific drug delivery are discussed.
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Affiliation(s)
- R Kinget
- Laboratorium voor Farmacotechnologie en Biofarmacie, Katholieke Universiteit Leuven, Belgium
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Rajendran VM, Binder HJ. Distribution and regulation of apical Cl/anion exchanges in surface and crypt cells of rat distal colon. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:G132-7. [PMID: 9886988 DOI: 10.1152/ajpgi.1999.276.1.g132] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Na depletion inhibits electroneutral Na-Cl absorption in intact tissues and Na/H exchange in apical membrane vesicles (AMV) of rat distal colon. Two anion (Cl/HCO3 and Cl/OH) exchanges have been identified in AMV from surface cells of rat distal colon. To determine whether Cl/HCO3 and/or Cl/OH exchange is responsible for vectorial Cl movement, this study examined the spatial distribution and the effect of Na depletion on anion-dependent 36Cl uptake by AMV in rat distal colon. These studies demonstrate that HCO3 concentration gradient-driven 36Cl uptake (i.e., Cl/HCO3 exchange) is 1) primarily present in AMV from surface cells and 2) markedly reduced by Na depletion. In contrast, OH concentration gradient-driven 36Cl uptake (i.e., Cl/OH exchange) present in both surface and crypt cells is not affected by Na depletion. In Na-depleted animals HCO3 also stimulates 36Cl via Cl/OH exchange with low affinity. These results suggest that Cl/HCO3 exchange is responsible for vectorial Cl absorption, whereas Cl/OH exchange is involved in cell volume and/or cell pH homeostasis.
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Affiliation(s)
- V M Rajendran
- Departments of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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Binder HJ, Singh SK, Geibel JP, Rajendran VM. Novel transport properties of colonic crypt cells: fluid absorption and Cl-dependent Na-H exchange. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART A, PHYSIOLOGY 1997; 118:265-9. [PMID: 9366054 DOI: 10.1016/s0300-9629(97)00079-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Colonic ion transport is heterogeneous including the long-accepted spatial separation of absorptive and secretory processes between surface and crypt cells. We recently described the isolation of individual crypts from the rat distal colon that were studied using microperfusion technology. Na-dependent fluid absorption was consistently demonstrated in these crypts during perfusion with a Ringer-like solution; dibutyryl cyclic AMP, VIP and acetylcholine, when added to the bath solution, all induced net fluid secretion. As several morphologic techniques, including immunocytochemistry, failed to provide evidence for the presence of myofibroblasts in the isolated crypt preparation, we propose that a Na-dependent absorptive process is a constitutive transport mechanism in crypt cells, while secretory processes are regulated by the release of one or more neurohumoral agonists from lamina propria cells including myofibroblasts. The mechanism of Na-dependent fluid movement was also studied by determining [H] gradient stimulation of 22Na uptake in isolated apical membrane vesicles (AMV) from crypt cells. In contrast to Na-H exchange in surface cell AMV, Na-H exchange in crypt cells is Cl-dependent. Intracellular pH determined in crypt cells using video-imaging fluorescence microscopy established that the response to an acid load requires both lumen Na and Cl. As a result, these studies have identified a novel Cl-dependent Na-H exchange in crypt AMV that may mediate apical membrane Na uptake and regulate pHi.
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Affiliation(s)
- H J Binder
- Department of Internal Medicine, Yale University, New Haven, Connecticut, USA.
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