Strain-specific differences in oxidative stress–related enzymes and ROS. (A, left) Equal amounts of total liver protein from three untreated and four DDC-fed C3H and C57BL mice were resolved by SDS-PAGE and immunoblotted with antibodies to Cyp2e1 or Cyp3a. The PRDX6 blot serves as a loading control. (right) Relative band intensity values of the blots were plotted for each strain/treatment group. ***, P < 0.001 using a two-way analysis of variance. Each tested group included three to four mice. Results are represented as the mean and the SD. (B) Isolated primary hepatocytes from C3H (panels a–d) and C57BL (panels e–h) mice were cultured in the presence of DDC or vehicle (0.1% DMSO), loaded with the ROS indicator CM-H₂DCFDA (panels a, b, e, and f) or immunostained for CBR3 (panels c, d, g, and h), and then mounted in the presence of DAPI as described in Materials and methods. Qualitative assessment of ROS levels (arrows in b and f) is based on CM-H₂DCFDA fluorescence (green). CBR3 appears as perinuclear particulates (arrows in panel h). Bars, 20 µm.