Figure 1. Effects of Zn²⁺ and Cd²⁺ on MDBK apoptosis.

(A) MDBK cells were treated with 10 μM CdCl₂, alone or in combination with ZnCl₂ (0, 10, or 50 μM), for 12 h. Apoptotic cell death was quantified by flow cytometry following double staining with propidium iodide (PI) and a fluorescein isothiocyanate (FITC)-conjugated annexin V antibody. Control cells were treated with medium. (B) MDBK cells were treated with CdCl₂ alone (0, 10, or 50 μM) or in combination with ZnCl₂ (0, 10, or 50 μM) for the indicated time periods. The percentage of PI- or annexin V-positive apoptotic cells was quantified by flow cytometry. The data were expressed as the mean ± SD (n = 4). #P<0.05, ##P<0.01, and ###P<0.001 for the comparison with the medium-treated control group; *P<0.05 and **P<0.01 compared to cells exposed to Cd²⁺ only (10 or 50 μM).