The effects of gentamicin and Cd2+ on cell membrane integrity. Animals were treated with either Cd2+ (0.6 mg/kg, sc 5 days a week for 6 weeks) or gentamicin (100 mg/kg ip per day for 8 days) and the left kidneys were infused with ethidium homodimer. Cryosections of the kidneys were then fixed, permeabilized and labeled with DAPI as described in the Methods section. Panels A-D are phase contrast images corresponding to DAPI-labeled panels E-H and ethidium homodimer labeled nuclei in panels I-L. Gentamicin treatment resulted in increased ethidium homodimer labeling (J) in the renal cortex as compared to control (I). No differences in ethidium homodimer labeling were detected in 6-week Cd2+-treated images (L) compared to control (K). The scale bar in the top left image represents 100 μm.