UT-B1 Mediates Transepithelial Urea Flux in the Rat Gastrointestinal Tract.
Summary of "UT-B1 Mediates Transepithelial Urea Flux in the Rat Gastrointestinal Tract."
The process of urea nitrogen salvaging plays a vital role in the symbiotic relationship between mammals and their intestinal bacteria. The first step in this process requires the movement of urea from the mammalian bloodstream into the gastrointestinal tract lumen via specialized proteins known as facilitative urea transporters. In this study, we examined both transepithelial urea fluxes and urea transporter protein abundance along the length of the rat gastrointestinal tract. Urea flux experiments that used rat gastrointestinal tissues showed significantly higher transepithelial urea transport was present in caecum and proximal colon (P < 0.01, n = 8, analysis of variance [ANOVA]). This large urea flux was significantly inhibited by 1,3,dimethylurea (P < 0.001, n = 8, ANOVA) and thiourea (P < 0.05, n = 6, unpaired t-test), both known blockers of facilitative urea transporters. Immunoblotting analysis failed to detect any UT-A protein within rat gastrointestinal tissue protein samples. In contrast, a 30-kDa UT-B1 protein was strongly detected in both caecum and proximal colon samples at significantly higher levels compared to the rest of the gastrointestinal tract (P < 0.01, n = 4, ANOVA). We therefore concluded that UT-B1 mediates the transepithelial movement of urea that occurs in specific distal regions of the rat gastrointestinal tract.
Affiliation
Institute for Clinical Outcomes Research and Education, St. Vincent's University Hospital, Dublin, Ireland.
Journal Details
This article was published in the following journal.
Name: The Journal of membrane biology
ISSN: 1432-1424
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/21127847
- DOI: http://dx.doi.org/10.1007/s00232-010-9331-9
Medical and Biotech [MESH] Definitions
Upper Gastrointestinal Tract
The segment of GASTROINTESTINAL TRACT that includes the ESOPHAGUS; the STOMACH; and the DUODENUM.
Serotonin
A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.
Lower Gastrointestinal Tract
The segment of GASTROINTESTINAL TRACT that includes the small intestine below the DUODENUM, and the LARGE INTESTINE.
Blood Urea Nitrogen
The urea concentration of the blood stated in terms of nitrogen content. Serum (plasma) urea nitrogen is approximately 12% higher than blood urea nitrogen concentration because of the greater protein content of red blood cells. Increases in blood or serum urea nitrogen are referred to as azotemia and may have prerenal, renal, or postrenal causes. (From Saunders Dictionary & Encyclopedia of Laboratory Medicine and Technology, 1984)
Gastrointestinal Motility
The motor activity of the GASTROINTESTINAL TRACT.
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