Batroxobin reduces intracellular calcium concentration and inhibits proliferation of vascular smooth muscle cells

Background. Batroxobin (BX), a serine protease used in defibrinogenation and thrombolysis, also has an effect on c-fos gene and growth factor. This study attempted to determine the effects of BX on the proliferation of vascular smooth muscle cells (VSMCs) and calcium metabolism. Methods. VSMCs were treated with BX at concentrations of 0.1, 0.3, or 1.0 mmol/L and cell numbers were determined at 0, 24, 48, and 72 hours. Intracellular calcium concentration ([Ca²⁺]_i) was measured using direct fluorescence methods. Results. BX was found to suppress proliferation of VSMCs in a dose-dependent fashion with inhibition rates of 18% and 31% by 48 and 72 hours, respectively. In addition, BX decreases basal [Ca²⁺]_i significantly. The basal level in untreated cells was 162.7±33.8 nmol/L, and decreased to 131.5±27.7 nmol/L, 128.3±28.5 nmol/L, and 125.6± 34.3 nmol/L with the three concentrations of BX, respectively. Noradrenaline (NE)-induced [Ca²⁺]_i stimulation was also attenuated by BX (0.1 mmol/L BX, 20%±8% inhibition; 0.3 mmol/L BX, 54%±11% inhibition; 1.0 mmol/L BX, 62%±15% inhibition). The ability of NE to stimulate [Ca²⁺]_i was attenuated in cultures in Ca²⁺-free medium, as was the ability of BX to blunt NE-induced stimulation. Conclusion. These findings demonstrate that BX can effectively inhibit proliferation of VSMCs, probably by blocking the release and uptake of Ca²⁺, thus influencing [Ca²⁺]_i.