PMID: 9435271Jan 22, 1998Paper

A thiamine/H+ antiport mechanism for thiamine entry into brush border membrane vesicles from rat small intestine

The Journal of Membrane Biology
U LaforenzaG Rindi

Abstract

Outwardly oriented H+ gradients greatly enhanced thiamine transport rate in brush border membrane vesicles from duodenal and jejunal mucosa of adult Wistar rats. At a gradient pHin5:pHout7.5, thiamine uptake showed an overshoot, which at 15 sec was three times as large as the uptake observed in the absence of the gradient. Under the same conditions, the binding component of uptake accounted for only 10-13% of intravesicular transport. At the same gradient, the Km and Jmax values of the saturable component of the thiamine uptake curve after a 6 sec incubation time were 6.2 +/- 1.4 microM and 14.9 +/- 3 pmol.mg-1 protein.6 sec-1 respectively. These values were about 3 and 5 times higher, respectively, than those recorded in the absence of H+ gradient. The saturable component of the thiamine antiport had a stoichiometric thiamine: H+ ratio of 1:1 and was inhibited by thiamine analogues, guanidine, guanidine derivatives, inhibitors of the guanidine/H+ antiport, and imipramine. Conversely, the guanidine/H+ antiport was inhibited by unlabeled thiamine and thiamine analogues; omeprazole caused an approximately fourfold increase in thiamine transport rate. In the absence of H+ gradient, changes in transmembrane electrical potential did...Continue Reading

Citations

Aug 15, 2006·Archives of Pharmacal Research·Moon Kyoung Kim, Chang-Koo Shim
Oct 22, 2003·Molecular Genetics and Metabolism·Judith C FlemingEllis J Neufeld
May 3, 2000·Kidney International·G GastaldiG Rindi
Aug 30, 2000·Proceedings of the Society for Experimental Biology and Medicine·G Rindi, U Laforenza
Nov 4, 2015·Molecular Pharmaceutics·Xiaomin LiangKathleen M Giacomini
Jan 1, 2005·Environmental Toxicology and Pharmacology·Perttu KoskiOlavi Pelkonen
Mar 6, 2012·European Journal of Pharmacology·Clara LemosConceição Calhau
Dec 25, 2004·Drug Metabolism and Pharmacokinetics·Toshiya Katsura, Ken-Ichi Inui
Nov 20, 2012·Alcohol and Alcoholism : International Journal of the Medical Council on Alcoholism·Ellen Rees, Linda R Gowing
Nov 5, 1999·The Journal of Biological Chemistry·B DuttaP D Prasad
Apr 14, 2000·American Journal of Physiology. Gastrointestinal and Liver Physiology·H MizuuchiK Inui
Aug 15, 2001·American Journal of Physiology. Cell Physiology·P K DudejaH M Said
Sep 27, 2000·American Journal of Physiology. Gastrointestinal and Liver Physiology·T KatsuraK I Inui
Jan 10, 2002·Biochimica Et Biophysica Acta·Anna VerriGianguido Rindi

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