POTTER, WZ, DC DAVIS, JR MITCHELL, DJ JOLLOW,. 1. R. GILLETTE AND B. B. BR0DIE: Acetaminopimen-induced imepatic necrosis. III. Cvtoclmrome P-450-mediated covaleimt binding in vitro. J. Pisarmacol. Exp. Timer. 187: 203-210, 1973.

Time binding of ‘H-acetaminopimen to imepatic microsomes was studied in vitro. Binmding of ‘H-acetaminophen to rat and mouse microsomal protein was linear with time anmd witim protein concentration. Binding occurred by covalent linkage to amino acids of protein. Reduced nicotinamide adenine dinueleotide pimospimate aisd oxygen were necessary for the binding wimile carbon monoxide or cobaitous chloride pretreatment inimibit. ed it, demonmstrating that a cvtocimrome P-450-dependent. mixed functionm oxidase mediated time binding. The extent of in vitro binding correlated witis treatmelmts tisat alter hepatic imecrosis and in vito binding, indicating that in vitro binding was a valid mmdcx of acetaminophen-induced hepatotoxicity. Analogous studies with 2-acetyiaminofluorene showed timat its bindinmg to microsomal protein also was dependent. on cvtochrome P-450. Since time toxicity of 2-acetylaminofluorene results from its conversion to an N-hydroxv derivative, time collective data are consistent with time imypotimesis timat the hepatotoxic metabolite of acetaminmopimen may he aim N-hydnoxy derivative.