| At present, the second incidence rate is tumor, which only less than the incidence rate of angiocardiopathy, and the tumor has been one of the dominating murderers of health of human being. According to the result of statistics by WHO, there are more than 40 millions cancer patients, and the incidence rate is increasing at the rate of 2-3% every year because of the process of industrialization and urbanization and the aggravation of pollution. Accordingly, it is very important and urgent to explore the efficient method for treating tumor.The current modalities of cancer treatment include surgery, chemotherapy, radiation therapy, immunotherapy, and their combinations. Some of these treatments have had some success in increasing the five-year or longer survival of certain cancer patients. However, they have some major limitations to these treatment modalities, for instance, the metastasis and relapse, multidrug resistance, severe side effects, poor immunocompetence, unresectable tumor associating with crucial organ, disfigurement associated with surgery, radiation-induced hair loss, and so on. These limitations often lead to the failure of therapy. Many investigations have been pursuing the development of the methods that would overcome these limitations. Therefore, a new method namedelectrochemotherapy is rising in the world. That is, utilizes electroporation as a means for delivering chemotherapeutic agents directly into tumor cells for treating tumor. There already have been some reports about electrochemotherapy in-vitro cell culture experiments and in-vivo experiments in animal models, and the effects were very good. The electrochemotherapy represent beautiful prospect. However, some major issues were still unanswered. These issues were as follows: first, the porative parameters and athermal effects of electromagnetic pulses on tumor cells were not studied; second, there was not any report about electrochemotherapy with low-intensity and low -frequence electromagnetic pulses; third, the security of electrochemotherapy was not studied; fourth, the kinds of drugs and tumor were limited, and no criterion of selecting drugs for electrochemotherapy was established; fifth, few mechanism of electrochemotherapy was analysed, and the electroporation was took for the only reason for enhancing the antitumor effects of electrochemotherapy. However, the newly documents show that the mechanism, which associates with the aspects of physics, biology, pharmacology, tumor, and so on, is complicated. It is very important to study electrochemotherapy for alleviating the patients' agony, enhancing patients' standard of living and making progress with the society.In this paper, the SI80 sarcoma cells was exposed to electromagnetic pulses with various intensity, pulses, capacitance (pulses breadth), and then the cell membrane, mitochondria, nucleus, endoplasmic reticulum, cell cycle, apoptosis rate, Superoxide Dismutase (SOD), Maleic Dialdehyde (MDA), were studied. As a result, the obstacle of permeability of cell membrane was inhibited, pore induced by electromagnetic pulses was discovered in 89.6+3% cells, and the diameter of pore was runs. The size and the distribution of pores were asymmetric. The microvillus of cell membrane was damaged, and the substance in cell was ejected out of cell. The cell cycle was changed with G2 periods which changed significantly. Mitochondria were changed with swelling, disappearance of ridge, endomembrane breakage. The chromatin was condensed, and the endoplasmic reticulum was swelling. The apoptosis rate of exposed cells rose by 7.8%, and it was significantly higher than that in control (P<0.05). Comparing the vitality of SOD and the concentration of MDA, it is shown that theelectromagnetic pulses hadn't significantly influenced the SOD and MDA.In vitro, the SI80 sarcoma cell in logarithmic phase was freely divided into four groups: control, electrotherapy group, chemotherapy group, electrochemotherapy group. Then, the cell cycle, apoptosis rate, vitality of SOD and concentration of MDA were studied. As a result, the apoptosis rate of electrochemotherapy, electrotherapy, chemotherapy, control was 44.1±3.1 % >7.1±1.9% *28.3±2.4% ,2.5±1.6%, respectively. The apoptosis rate in electrochemotherapy was significantly higher than that in chemotherapy, electrotherapy and control (P<0.05). The vitality of SOD in electrochemotherapy, electrotherapy, chemotherapy, control was 38.24±1.39 , 31.87+1.59, 36.05±1.56> 33.58±2.98, respectively. The vitality of SOD in electrochemotherapy was significantly higher than that in electrotherapy (P<0.05). The concentration of MDA in electrochemotherapy, electrotherapy, chemotherapy, control was 4.38±1.86> 6±1.41 > 4.14±0.43> 7.34+1.13, respectively. The concentration of MDA in electrochemotherapy was significantly lower than that in control (P<0.05).In vivo, the S180 sarcoma was modeled through KM mice, and then the tumor-bearing mice were freely divided into four groups: control, electrotherapy group, chemotherapy group and electrochemotherapy group. Furthermore, the normal mice without tumor were saved as negative control. Then, the tumor inhibiting rate, cure rate, SOD, MDA, Catalase (CAT), liver function, kidney function, index of liver and spleen, conductivity, dielectric constant, were studied. The vascular endothelial growth factor (VEGF) and microvessel density (MVD) were determined by the immunohistochemical method. The change of histopathology in tumor was studied by the histopathological method. As a result, the inhibiting rate and cure rate of electrochemotherapy were both significantly higher than in chemotherapy and electrotherapy. This indicated that the electrochemotherapy had significantly enhanced the antitumor effects of drug. Through analyzing, the cure rate in electrochemotherapy was higher than the summation of that in electrotherapy and chemotherapy. So this indicated that electromagnetic pulses combining with drugs have synergetic effect. The vitality of SOD and CAT in electrochemotherapy was significantly enhanced, and the concentration of MDA in electrochemotherapy was significantly decreased. Theantioxidant competence of organ was enhanced while the level of injury by free radical was decreased. The function of liver and kidney, index of liver between electrochemotherapy was not significant different from that in control and negative control. So it indicated that electrochemotherapy had more security and less side effects. The index of spleen in electrochemoth^mpy was significantly lower than that in control while not significantly different from negative control, so it indicated that electrochemotherapy could enhance the competence of immunity. To the dielectric constant and conductivity, there wasn't any difference between the control, electrotherapy, chemotherapy, electrochemotherapy and negative control, and this indicated that the characters of electrics were not changed significantly. The positive expression rate of VEGF in electrochemotherapy was significantly lower than that in electrotherapy and chemotherapy. Likewise, the MVD in electrochemotherapy was significantly lower than that in electrotherapy and chemotherapy. The results of VEGF and MVD indicated that electrochemotherapy had significantly inhibited the expression of VEGF and the growth of microvessel of tumor. The histopathologic section of tumor indicated that the cells in electrochemotherapy were mostly apoptosis. The matrix of tumor had putrescence area with eosine dye. And cell debris was found in tumor. The cells in control were with characteristics of large nucleus with deep dyeing, large proportion of nucleus cytoplasm, and the most nucleus cleavage were found. The cure rate of electrochemotherapy of Bleomycin was enhanced by 57.94% comparing to chemotherapy of Bleomycin. The cure rate of electrochemotherapy of Cytoxan is enhanced by 43.42% comparing to chemotherapy of Cytoxan. Therefore, the level of antitumor effects in electrochemotherapy of Bleomycin was significantly higher than that in electrochemotherapy of Cytoxan. It also indicated the enhancing level of antitumor effects is different by using different drugs, and it associated with the character of drugs. The activity and diet of mice in each group was normal after the treatment. The edema of tumor was discovered after the mice were treated by electromagnetic pulses. Then, the edema disappears and the scabs on the surface of tumor were observed a few days later. In conclusion, the electrochemotherapy had significantly enhanced the antitumor effects of antitumor drugs and the immunitycompetence of mice, and the method also had the merit of more security, lower side effects and simpler operation.At the basis of experiment, the mechanism of electrochemotherapy may be as follows: 1), through electroporation, the drugs freely enter into cytoplasm, and the concentration of drugs is enhanced, which lead to the antitumor effects enhanced. 2), the expression of VEGF and growth of microvessel is inhibited, and the blood fluxion through tumor is inhibited, then the provison of nutrition is stoped or decreased. 3), the immunity competence is advanced in the course of treatment, and the immunity system also inhibit tumor in a part. 4), the antioxidant competence is improved, and the production and elimination of free radical keeps dynamic balance. 5), not only does the electromagnetic pulses has antitumor effects, but also it improve the sensitivity of tumor cell to drugs. There are the synergistic effects of various anticancer drugs combining with pulsed electric fields. 6), the antitumor effects of electrochemotherapy associates with both the patameters and drug's character of physics and chemistry and pharmacological action.
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