Effects of P-glycoprotein inhibitors on cadmium accumulation in cultured renal epithelial cells, LLC-PK1, and OK.
The purpose of this study was to investigate whether cadmium (Cd) efflux across the apical membrane of cultured renal epithelial cells, LLC-PK(1) and OK, is mediated via P-glycoprotein (P-gp). These cells were preincubated for 30 min with a typical P-gp inhibitor such as verapamil, diltiazem, nifedipine, vinblastine, or cyclosporin A before the incubation with 1 microM (109)CdCl(2) for 15 min. Preincubation with each P-gp inhibitor significantly increased Cd accumulation in LLC-PK(1), and OK cells. Treatment of these cells with UIC2, a P-gp monoclonal antibody, also significantly increased Cd accumulation in these cells. Thus, the pretreatment of cells with P-gp inhibitor appears to increase Cd accumulation as a result of the inhibition of Cd efflux via P-gp. To confirm Cd efflux via P-gp, Cd accumulation in P-gp-overexpressed cells (LLC-GA5-COL150 cells) was compared with that in parental LLC-PK(1) cells. LLC-GA5-COL150 cells accumulated less Cd than did LLC-PK(1) cells, and the effects of the P-gp inhibitors and UIC2 on Cd accumulation were greater in LLC-GA5-COL150 cells. These results suggest that P-gp in LLC-PK(1) and OK cells appear to act as an efflux pump of Cd, decreasing cellular Cd accumulation.
Endo
Tetsuya
T
Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757, Ishikari-Tobetsu, Hokkaido 061-0293, Japan. endotty@hoku-iryo-u.ac.jp
Kimura
Osamu
O
Sakata
Masakatsu
M
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors*; D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002104:Cadmium / Q000378:metabolism*; D002106:Cadmium Radioisotopes; D002121:Calcium Channel Blockers / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005456:Fluorescent Dyes; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D018374:LLC-PK1 Cells; D014176:Protein Biosynthesis; D051381:Rats; D020112:Rhodamine 123; D013552:Swine; D014747:Vinblastine / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D002106:Cadmium Radioisotopes; D002121:Calcium Channel Blockers; D005456:Fluorescent Dyes; D002104:Cadmium; D020112:Rhodamine 123; D014747:Vinblastine; D016572:Cyclosporine