RESUMO
<p><b>OBJECTIVE</b>To explore the role of Ca(2+) in nanosecond steep pulse (NSP)-induced apoptosis of human ovarian carcinoma cell line SKOV3 in vitro.</p><p><b>METHODS</b>The early apoptotic rate of SKOV3 cells treated with NSP was detected by Annexin V/PI double staining and flow cytometry. MTT assay was used to detect the viability of the cells pretreated with BAPTA-AM (0, 25, 50 and 100 µmol/L) chelation for 1 h to increase the intracellular free Ca(2+) prior to NSP exposure, and the cell morphological changes and caspase 12 expression were detected using Hoechst 33342 staining and Western blotting, respectively.</p><p><b>RESULTS</b>Flow cytometry showed that NSP induced early apoptosis of SKOV3 cells, and the optimal effect was achieved with the treatment parameter configuration of field strength of 90 kV/cm, pulse width of 100 ns, frequency of 1 Hz, and exposure time of 30 s. The highest early apoptotic rate and necrosis rate was (60.31∓5.67)% and (1.35∓0.39)%, respectively. Pretreatment with BAPTA-AM chelation prior to NSP exposure significantly increased the cell viability (P<0.05), and resulted also in lowered apoptosis rate and decreased expression of caspase 12 (P<0.05).</p><p><b>CONCLUSION</b>NSP can induce apoptosis in SKOV3 cells. Increased intracellular free Ca(2+) functions as an important mediator in NSP-induced cell apoptosis, which may also involve Ca(2+)-mediated endo- plasmic reticulum pathway.</p>