Role of Cytochrome P450s in 2,4,5‐Trichlorophenol Nephrotoxicity in Isolated Kidney Cells from Male Fischer 344 Rats

Abstract

Trichlorophenols (TCPs) are used as chemical intermediates in the manufacture of a wide range of agricultural and industrial products. Previous studies have shown that 2,4,5‐TCP is the most potent nephrotoxicant in vitro of the six TCP isomers in isolated kidney cells (IKCs) from male Fischer 344 rats. It was also determined that 2,4,5‐TCP nephrotoxicity was attenuated by piperonyl butoxide, a non‐specific cytochrome P450 (CYP) inhibitor. The purpose of this study was to determine which CYPs might play a role in 2,4,5‐TCP nephrotoxicity in vitro in IKCs from male Fischer 344 rats. IKCs (~4 million/ml, 3 ml) were incubated with a selective CYP inhibitor or vehicle prior to addition of 2,4,5‐TCP (0.5 mM) or dimethyl sulfoxide (DMSO, 2,4,5‐TCP vehicle) for 60 min with shaking at 37oC under a 95% oxygen/5% carbon dioxide atmosphere. Cytotoxicity was determined by measuring lactate dehydrogenase (LDH) release at the end of the incubation period. 2,4,5‐TCP‐induced cytotoxicity was completely attenuated by CYP inhibitors sulfaphenazole (CYP2C11) and thiotepa (CYP2B6). 2,4,5‐TCP cytotoxicity was also reduced by pretreatment with omeprazole (CYP2C19), DEDTCA (CYP2C/E), or isoniazid (CYP2E1). The least effective CYP inhibitor at reducing 2,4,5‐TCP cytotoxicity was oleandomycin (CYP3A). These results suggest that CYPs play a role in 2,4,5‐TCP nephrotoxicity in vitro with CYP2C11 and CYP2B6 being major contributors to promoting 2,4,5‐TCP cytotoxicity. The mechanism by which these and other CYPs promote 2,4,5‐TCP nephrotoxicity remains to be determined.