Metabolism of the nephrotoxicant N-(3,5-dichlorophenyl)succinimide by isolated rat hepatocytes.

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is nephrotoxic in rats, and hepatic biotransformation appears to be involved in the metabolic activation of this compound. NDPS metabolism was therefore investigated in vitro using hepatocytes isolated from male Fischer 344 rats. Cells were incubated with NDPS at 37 degrees C, and metabolites were analyzed by reversed-phase HPLC with UV (254 nm) and radiochemical detection. HPLC peaks were identified by comparison with synthetic standards. The following oxidative metabolites were detected: N-(3,5-dichlorophenyl)-2- hydroxysuccinamic acid (2-NDHSA); N-(3,5-dichlorophenyl)-3-hydroxysuccinamic acid; N-(3,5-dichlorophenyl)-2-hydroxysuccinimide; and N-(3,5-dichloro-4-hydroxyphenyl)succinamic acid. Formation of the major oxidative product, 2-NDHSA, followed Michaelis-Menten kinetics and yielded apparent KM and Vmax values of 1.76 +/- 0.39 mM and 31.01 +/- 3.93 nmol/10(6) cells/hr, respectively. Based on inhibition studies, the formation of these products was mediated by cytochrome(s) P450. The hydrolysis product N-(3,5-dichlorophenyl)succinamic acid was generated nonenzymatically under all incubation conditions. There was no evidence for the formation of glucuronide, sulfate, or glutathione conjugates. Cell viability studies showed that NDPS and its metabolites were not cytotoxic to the isolated hepatocytes. Data demonstrate that isolated hepatocytes can be used to characterize the metabolism of NDPS and may be useful in elucidating the role of the liver in NDPS-induced nephrotoxicity.