Linked Life Data

11230729

Source:http://linkedlifedata.com/resource/pubmed/id/11230729

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2001-3-14
pubmed:abstractText
Canalicular transport via the bile salt export pump (Bsep) represents the rate-controlling step in taurocholate excretion, whose capacity is under osmotic control. The short-term effects of anisoosmolarity and Ca(2+)-withdrawal on the localization of Bsep and the tight junction proteins Zo-1 and occludin were studied in perfused rat liver by immunohistochemistry, confocal microscopy, and densitometry. Under normoosmotic conditions, Bsep was found in the canalicular membrane and showed a punctate intracellular localization. Hypoosmolarity resulted in the translocation of intracellular Bsep to the canalicular membrane, whereas hyperosmolarity induced a retrieval of Bsep. Following hyperosmolar retrieval of Bsep and multidrug resistance protein 2 (Mrp2) from the canalicular membrane, in the putative intracellular vesicles Bsep and Mrp2 colocalized in 15% of these vesicles, whereas 85% stained either positive for Bsep (61%) or Mrp2 (24%). Anisotonicity had no effect on the linear staining patterns of occludin and Zo-1, indicating no increase in paracellular permeability. Omission of calcium produced cholestasis characterized by a disruption of occludin, whereas the localization of Zo-1, Bsep, and Mrp2 remained unaffected. It is concluded (1) that hyperosmolarity induces retrieval of Bsep from the canalicular membrane, which correlates to cholestasis. Hypoosmolarity leads to choleresis accompanied by a rapid recruitment of intracellular Bsep to the canalicular membrane. (2) Bsep- and Mrp2-specific vesicles participate in the short-term osmoregulation of canalicular secretion, however, a cause-effect relationship between bile salt excretion and transporter localization remains to be established. (3) Ca(2+)-depletion induces cholestasis by disruption of occludin-determined tight junctional permeability, whereas internalization of canalicular transporters play a minor role.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0270-9139
pubmed:author
pubmed:issnType
Print
pubmed:volume
33
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
509-18
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Regulation of the dynamic localization of the rat Bsep gene-encoded bile salt export pump by anisoosmolarity.
pubmed:affiliation
Medizinische Universitätsklinik, Heinrich Heine Universität, Düsseldorf, Germany. marcus.schmitt@uni-duesseldorf.de
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't