Ileal mucosal bile acid absorption is increased in Cftr knockout mice

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Ileal mucosal bile acid absorption is increased in Cftr knockout mice

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dc.contributor.author Stelzner, Matthias en_US
dc.contributor.author Somasundaram, Sivagurunathan en_US
dc.contributor.author Lee, Sum P. en_US
dc.contributor.author Kuver, Rahul en_US
dc.date.accessioned 2010-04-21T15:56:29Z
dc.date.available 2010-04-21T15:56:29Z
dc.date.issued 2001-10-15 en_US
dc.identifier.citation Stelzner M, Somasundaram S, Lee S, Kuver R. Ileal mucosal bile acid absorption is increased in Cftr knockout mice. BMC Gastroenterology. 2001;1(1):10. en_US
dc.identifier.other 10.1186/1471-230X-1-10 en_US
dc.identifier.uri http://www.biomedcentral.com/1471-230X/1/10 en_US
dc.identifier.uri http://hdl.handle.net/1773/15778
dc.description.abstract Background: Excessive loss of bile acids in stool has been reported in patients with cystic fibrosis. Some data suggest that a defect in mucosal bile acid transport may be the mechanism of bile acid malabsorption in these individuals. However, the molecular basis of this defect is unknown. This study examines the expression of the ileal bile acid transporter protein (IBAT) and rates of diffusional (sodium independent) and active (sodium dependent) uptake of the radiolabeled bile acid taurocholate in mice with targeted disruption of the cftr gene. Methods: Wild-type, heterozygous cftr (+/-) and homozygous cftr (-/-) mice were studied. Five one-cm segments of terminal ileum were excised, everted and mounted onto thin stainless steel rods and incubated in buffer containing tracer 3H-taurocholate. Simultaneously, adjacent segments of terminal ileum were taken and processed for immunohistochemistry and Western blots using an antibody against the IBAT protein. Results: In all ileal segments, taurocholate uptake rates were fourfold higher in cftr (-/-) and twofold higher in cftr (+/-) mice compared to wild-type mice. Passive uptake was not significantly higher in cftr (-/-) mice than in controls. IBAT protein was comparably increased. Immuno-staining revealed that the greatest increases occurred in the crypts of cftr (-/-) animals. Conclusions: In the ileum, IBAT protein densities and taurocholate uptake rates are elevated in cftr (-/-) mice > cftr (+/-) > wild-type mice. These findings indicate that bile acid malabsorption in cystic fibrosis is not caused by a decrease in IBAT activity at the brush border. Alternative mechanisms are proposed, such as impaired bile acid uptake caused by the thick mucus barrier in the distal small bowel, coupled with a direct negative regulatory role for cftr in IBAT function. en_US
dc.language.iso en_US en_US
dc.title Ileal mucosal bile acid absorption is increased in Cftr knockout mice en_US


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