Fluorescein-methotrexate transport in brush border membrane vesicles from rat small intestine.
The transport characteristics of fluorescein-methotrexate (F-MTX) in isolated brush border membrane vesicles (BBMVs) from rat small intestine were studied. F-MTX uptake in BBMVs was measured by a rapid filtration technique. Our results demonstrated that F-MTX uptake into vesicles was 1) significantly increased under the experimental conditions of an outwardly directed OH(-) gradient or an inwardly directed H(+)gradient, 2) sensitive to temperature, 3) increased with decreasing pH of the incubation buffer, 4) significantly inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) at the early stage of the uptake, and 5) significantly inhibited by methotrexate (MTX). Thus, the transport of F-MTX in BBMVs was shown to be mediated in part by the reduced folate transporter (RFC) which was known to transport MTX through the epithelium of small intestine.
Li
Tiesong
T
Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, 263-8522 Chiba, Japan.
Tomimatsu
Takashi
T
Ito
Kousei
K
Horie
Toshiharu
T
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000378:metabolism*; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism; D019793:Fluorescein / Q000378:metabolism*; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000378:metabolism*; D008297:Male; D026901:Membrane Transport Proteins; D008727:Methotrexate / Q000031:analogs & derivatives / Q000378:metabolism*; D008871:Microvilli / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D058978:Reduced Folate Carrier Protein; D013696:Temperature
D000964:Antimetabolites, Antineoplastic; D002352:Carrier Proteins; D005456:Fluorescent Dyes; D026901:Membrane Transport Proteins; D058978:Reduced Folate Carrier Protein; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D019793:Fluorescein; D008727:Methotrexate