Comparative inhibitory effects of different compounds on rat oatpl (slc21a1)- and Oatp2 (Slc21a5)-mediated transport.
OBJECTIVE
The purpose of the present study is to examine the selectivity of various inhibitors towards the rat organic anion transporting polypeptides 1 (Oatp1: gene symbol Slc21a1) and 2 (Oatp2: Slc21a5).


METHODS
The inhibitory effects of 20 compounds on the Oatpl-mediated transport of estradiol 17beta-D-glucuronide and on the Oatp2-mediated transport of digoxin were examined in cDNA-transfected LLC-PK1cells.


RESULTS
Among the compounds examined in this study, nonsteroidal anti-inflammatory drugs, deoxycorticosterone. and quinidine preferentially inhibited Oatpl. whereas digoxin, quinine, and rifampicin preferentially inhibited Oatp2 at low concentrations. On the other hand, propionic acid, re-ketoglutarate and p-aminohippurate showed no inhibitory effects on either transporter up to a concentration of 1,000 microM. The Ki values of ibuprofen and quinidine were estimated to be 19 and 13 times lower for Oatpl compared with Oatp2, whereas the values for rifampicin, quinine, and digoxin were 13, 20, and 100< times lower for Oatp2 compared with Oatpl.


CONCLUSIONS
At low concentrations, some of the tested inhibitors exert selective inhibition of either Oatpl- or Oatp2-mediated substrate transport. These selective inhibitors may be used at appropriate concentrations to estimate the maximum contribution of Oatp1 or Oatp2 to the total substrate uptake into rat hepatocytes.
Shitara
Yoshihisa
Y
School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.
Sugiyama
Daisuke
D
Kusuhara
Hiroyuki
H
Kato
Yukio
Y
Abe
Takaaki
T
Meier
Peter J
PJ
Itoh
Tomoo
T
Sugiyama
Yuichi
Y
D000465:Algorithms; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D000904:Antibiotics, Antitubercular / Q000494:pharmacology; D000962:Antimalarials / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D004077:Digoxin / Q000378:metabolism / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000378:metabolism; D007052:Ibuprofen / Q000494:pharmacology; D018374:LLC-PK1 Cells; D027361:Organic Anion Transporters; D029362:Organic Anion Transporters, Sodium-Independent / Q000037:antagonists & inhibitors*; D027701:Organic Cation Transport Proteins / Q000037:antagonists & inhibitors*; D011802:Quinidine / Q000494:pharmacology; D011803:Quinine / Q000494:pharmacology; D051381:Rats; D012293:Rifampin / Q000494:pharmacology; D013552:Swine
D000894:Anti-Inflammatory Agents, Non-Steroidal; D000904:Antibiotics, Antitubercular; D000962:Antimalarials; D004791:Enzyme Inhibitors; D027361:Organic Anion Transporters; D029362:Organic Anion Transporters, Sodium-Independent; D027701:Organic Cation Transport Proteins; C421102:Slco1a1 protein, rat; C503597:Slco1a4 protein, rat; C451262:Slco1c1 protein, rat; D004958:Estradiol; D004077:Digoxin; D011803:Quinine; D011802:Quinidine; D012293:Rifampin; D007052:Ibuprofen