Toxic Effect of Verapamil on Human Peripheral Blood Mononuclear Cells and BALB/c Peritoneal Macrophages, in vitro

Background & Aims: Verapamil as a calcium channel blocker has been broadly used in the treatment of many cardiovascular diseases such as hypertension and arrhythmia. Furthermore, the anti-tumor/ antiinflammatory effects of verapamil have been shown. In the present study, the cytotoxic effect of verapamil on human peripheral blood mononuclear cells (PBMCs) and BALB/c peritoneal macrophges has been evaluated in vitro. Methods: Human PBMCs and BALB/c peritoneal macrophges were cultured in complete RPMI medium. Then the cells at logarhytmic growth phase were incubated with different concentrations of verapamil (2×10-6 - 2×10-3M) for 24, 48 and 72 hours. Subsequently the cell proliferation was assessed with Trypan blue dye exclusion and MTT 3-[4, 5-dimethyl thiazol-2, 5-diphenyltetrazoliumbromide] methods. Results: Verapamil significantly decreased the proliferation of the human PBMCs and BALB/c peritoneal macrophges dose dependently. This cytotoxic effect was shown at 1 mM concentration of the verapamil after 24h incubation time onwards Moreover, the cytotoxic effect of verapamil at 1mM concentration of the drug increased with time in this order: 24h> 48h>72h. Conclusions: In this study, verapamil showed a dose -dependent cytotoxic effect on the human PBMCs and BALB/c peritoneal macrophges. Since the cytotoxic dose of verapamil on normal cells showed in this study was much higher than that reported for tumor cells, it seems that tumor cells may be more sensitive to verapamil than normal cells. Thus, verapamil could have potential implication in the treatment of cancers.