Fig. 5.

Effect of quinidine on EROD and MROD activities catalyzed by recombinant human CYP1A1, CYP1A2, and liver microsomes from Cyp1a KO mice at different substrate concentrations. EROD (A, C, and E) and MROD (B, D, and F) catalyzed by recombinant human CYP1A1 (A and B), CYP1A2 (C and D), and liver microsomes from TCDD-treated Cyp1a KO mice (E and F) at different concentrations of substrate and quinidine, as detailed in Materials and Methods. Symbols are the measured reaction rates. Lines are nonlinear regression analysis of the data using eqs. 1–6 (for details, see Data Analysis in the Supplemental Materials).