中文摘要：

目的观察不同频率脉冲电场对离体人卵巢癌SKOV3的急性细胞毒性及对BALB／e裸鼠SKOV3皮下移植瘤的迟发性抑制效应，以探讨电场脉冲频率与急、慢性抑制效应间的量效关系。方法首先梯度改变脉冲频率（1，60，1000，5000Hz）和电压峰值（50，100，150，200，250，300，350，400V），对SKOV3离体细胞悬液进行电击刺激。采用四甲基偶氮唑盐法（MTT）检测脉冲电场的急性细胞毒性效应；然后仅梯度改变电场脉冲频率（1，60，1000，5000Hz），依次对28只BALB／c裸小鼠SKOV3皮下移植瘤进行电脉冲刺激，对照组（7只）皮下移植瘤仅插入电极，但未给予电脉冲刺激。采用体积抑瘤率来观察脉冲电场的迟发性抑瘤效应；采用光、电镜观察SKOV3组织学超微结构变化。结果频率为1Hz及5kHz的脉冲电场对离体SKOV3有着相似的急性细胞毒性效应；各频率脉冲电场对小鼠皮下移植瘤的迟发性抑制效应亦无明显差异（P〉0．05）；组织学分析发现各频率脉冲电场均对靶组织造成急性损伤效应，而且5kHz脉冲电场还能诱导SKOV3离体细胞或在体瘤细胞凋亡。结论5kHz脉冲电场相对低频（1Hz）脉冲电场并未减弱其对肿瘤组织的急、慢性抑制效应，并且还具有诱导细胞凋亡的二线杀伤效应。

英文摘要：

Objective To investigate acute cell damage and delayed inhibition effects by pulsed electric fields （PEFs） with different frequencies on human ovarian carcinoma cell line SKOV3 in vitro and in subcutaneous transplanted tumor of human SKOV3 in BALB/e nude mice, and evaluate the potential use of relatively higher frequency PEFs to reduce unpleasant sensations without decreasing therapeutic effects in clinical eleetroehemotherapy. Methods Firstly, SKOV3 cell suspension were exposed to PEFs with gradient increasing frequencies （ 1,60,1 000, 5 000 Hz） and voltages （50,100,150,200,250,300,350,400 V） , respectively, MTT assay was used to determine the acute cell damage. Then PEFs with gradient increasing frequencies （1, 60, 1 000, 5 000 Hz） and fixed voltage （250 V） were applied to the subcutaneously transplanted tumor, in vivo antitumor assay was used to observe the delayed inhibition effect; histological changes were observed by light and electron microscope. Results The 1 Hz PEFs has similar eytotoxie effects with 5 kHz, and no significant difference of delayed tumor inhibition effect on subcutaneous transplanted tumor among all groups exposed to different frequencies of PEFs （ P 〉 0.05 ）. Histological observation showed acute damage in all exposed groups, and only in 5 kHz group was induced apoptotle effect observed. Conclusions PEFs with relatively higher frequency can achieve similar tumor killing effect with the low frequency PEFs, and it can also induce apoptosis. Relatively higher frequency PEFs show therapeutic potentials for reducing unpleasant sensations in clinical electrical treatment of tumor.