Comparative analysis of the ontogeny of a sodium dependent bile
acid transporter in the rat kidney and ileum.
Christie, Donna Marie, Paul A. Dawson, Sundararajah Thevananther, and
Benjamin L. Shneider.
Department of Pediatrics, Division of Pediatric
Gastroenterology/Hepatology, Yale University School of Medicine, New
Haven, CT, 06520 and the Department of Internal Medicine
Gastroenterology, Bowman Gray School of Medicine, Wake Forest
University, Winston-Salem, NC, 27157
APStracts 3:0016G, 1996.
An apical sodium dependent bile acid transporter (ASBT1) has recently
been cloned and characterized in the rat ileum. Northern and western
blotting revealed both the ASBT mRNA and protein in rat kidney. The
coding sequence of the kidney transcript was found to be identical to
the previously cloned ileal ASBT. Indirect immunofluorescence studies
localized the ASBT protein to the apical membrane of the renal
proximal convoluted tubule. Kinetic analysis of sodium-dependent
taurocholate uptake using membrane vesicles revealed similar K[mu]
values in the kidney and intestine. ASBT protein and function were
present in kidney but not ileum from 7 day old rats. On postnatal day
seven there was a seven-fold increase in ASBT steady-state mRNA
levels in kidney relative to ileum, yet nuclear run on assays
revealed that the nascent transcription rates at this age were
virtually the same. This suggests that the difference in the neonatal
expression of the ASBT gene in the kidney and ileum may be in part
due to differences in mRNA stability.
Received 30 August 1995; accepted in final form 3 January 1996.
APS Manuscript Number G378-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 January 96