Evaluation of chromosomal aberrations induced by hydralazine in Chinese hamster ovary cells

Background and purpose: Hydralazine (HDZ) is a cardiovascular drug that is widely used to treat hypertension. The present study was done to assess the cytogenetic effects of HDZ on Chinese hamster ovary (CHO) cells. Materials and methods: Methylthiazol tetrazolium (MTT) assay was carried out to determine the half maximal inhibitory concentration (IC50) of the drug. The IC50 value for HDZ was 243.3 ± 16.9 μg/ml. To investigate the clastogenic effects of the drug, chromatid breaks and polyploidy in metaphases were analyzed. CHO cells were exposed to different concentrations of HDZ (20 and 40 μg/ml) for 24 h. The experiments were carried out in the presence and absence of metabolic activation system (S9 mix; 1 ml S9 mix contained: 0.3 ml phosphate solutions, 0.2 ml KCl, 0.2 ml MgCl2, 0.1 ml S9 fraction, 0.1 ml G-6-P and 0.1 ml NADP), because HDZ is metabolized in the liver. Mitomycin-C and sodium arsenite were used as positive controls. Results: In the absence of S9 fraction, the level of chromatid breaks statistically increased (P = 0.011) and mitotic index significantly decreased (P < 0.001) in CHO cells treated with HDZ. There was no significant difference between treated and untreated CHO cells with HDZ for the level of polyploidy (F = 0.05; df = 2, 6; P = 0.945). In the presence of S9 fraction, although the mitotic index elevated, still there was a significant difference between control and treated cells (F = 50.53; df = 2, 6; P < 0.001). There was no significant difference between 20 μg/ml of HDZ (+S9) and untreated cells for frequency of chromatid breaks. However, at the 40 μg/ml concentration of HDZ (+S9), there was a significant difference between treated and untreated cells. Conclusion: HDZ have genotoxic effects on CHO cells in their non-toxic dose, but S9 mix addition decreased these effects