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Region-dependent modulation of intestinal permeability by drug efflux transporters: In vitro studies in mdr1a(-/-) mouse intestine

Stephens, RH, Tanianis-Hughes, J, Higgs, NB, Humphrey, M and Warhurst, G 2002, 'Region-dependent modulation of intestinal permeability by drug efflux transporters: In vitro studies in mdr1a(-/-) mouse intestine' , Journal of Pharmacology and Experimental Therapeutics, 303 (3) , pp. 1095-1101.

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Abstract

Information on the extent to which xenobiotics interact with P-glycoprotein (PGP) during transit through the intestine is crucial in determining the influence of PGP on oral drug absorption. We have recently described a novel use of isolated ileum from PGP-deficient mdr1a(-/-) mice to resolve PGP- and non-PGP-dependent drug efflux and provide a definitive measure of intrinsic drug permeability without recourse to inhibitors (Stephens et al., 2002). The present study uses this approach to investigate the impact of PGP on intestinal permeability of paclitaxel and digoxin in different regions of the mouse intestine (jejunum, ileum, and proximal and distal colon). Absorption of paclitaxel and digoxin in tissues from wild-type mice was low and showed little regional variation. In contrast, absorption of both drugs was markedly higher in mdr1a(-/-) intestine, although the increase was highly region-dependent, with the ileum and distal colon showing the greatest effect and much smaller changes in the jejunum and proximal colon. These effects were accompanied by the abolition of paclitaxel and digoxin secretion in mdr1a(-/-) mice, suggesting that regional variations in intestinal permeability are masked by differential PGP expression, confirmed by immunoblotting studies. Propranolol permeability, which is not influenced by PGP, showed similar regional variation in both wild-type and mdr1a(-/-) tissues, suggesting that differences are at the level of transcellular permeability. These data suggest that the ileum and the distal colon are regions of relatively high transcellular permeability for xenobiotics that are compensated by enhanced expression of PGP.

Item Type: Article
Themes: Subjects / Themes > R Medicine > R Medicine (General)
Health and Wellbeing
Schools: Colleges and Schools > College of Science & Technology
Colleges and Schools > College of Science & Technology > School of Environment and Life Sciences
Colleges and Schools > College of Science & Technology > School of Environment and Life Sciences > Ecosystems and Environment Research Centre
Journal or Publication Title: Journal of Pharmacology and Experimental Therapeutics
Publisher: American Society for Pharmacology and Experimental Therapeutics
Refereed: Yes
ISSN: 1521-0103
Depositing User: H Kenna
Date Deposited: 20 Aug 2007 15:04
Last Modified: 20 Aug 2013 16:46
URI: http://usir.salford.ac.uk/id/eprint/255

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