Fluorescein transport properties across artificial lipid membranes, Caco-2 cell monolayers and rat jejunum.
Membrane transport characteristics of a paracellular permeability marker fluorescein were evaluated using artificial membrane, Caco-2 cell monolayers and rat jejunum, all mounted in side-by-side diffusion cells. Modified Ringer buffers with varied pH values were applied as incubation salines on both sides of artificial membrane, cell culture monolayers or rat jejunum. Passive transport according to pH partition theory was determined using all three permeability models. In addition to that, active transport of fluorescein in the M-S (mucosal-to-serosal) direction through rat jejunum was observed. The highest M-S P(app) values regarding the active transport through the rat jejunum were observed in incubation saline with pH 6.5. Fluorescein transport through the rat jejunum was inhibited by DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid) and alpha-CHC (alpha-cyano-4-hydroxycinnamic acid). Thus, we assume that two pH-dependent influx transporters could be involved in the fluorescein membrane transport through the intestinal (jejunal) epithelium. One is very likely an MCT (monocarboxylic acid cotransporter) isoform, inhibited by specific MCT inhibitor alpha-CHC, while the involvement of the second one with overlapping substrate/inhibitor specificities (most probably a member of the organic anion-transporting polypeptide family, inhibited at least partially by DIDS) could not be excluded.
Berginc
Katja
K
Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia. katja.sturm@ffa.uni-lj.si
Zakelj
Simon
S
Levstik
Lea
L
Ursic
Darko
D
Kristl
Albin
A
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D002021:Buffers; D018938:Caco-2 Cells; D002463:Cell Membrane Permeability / Q000187:drug effects; D003101:Collodion / Q000378:metabolism*; D003373:Coumaric Acids / Q000494:pharmacology; D004058:Diffusion; D015194:Diffusion Chambers, Culture; D019793:Fluorescein / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008567:Membranes, Artificial; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism; D009924:Organ Culture Techniques; D027361:Organic Anion Transporters / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D002021:Buffers; D003373:Coumaric Acids; D005456:Fluorescent Dyes; D008567:Membranes, Artificial; D027501:Monocarboxylic Acid Transporters; D027361:Organic Anion Transporters; C007175:alpha-cyano-4-hydroxycinnamate; D003101:Collodion; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D019793:Fluorescein