Development of a dose-planning method for electrochemical treatment of tumors: A study of mammary tissue in healthy female CD rats

Many researchers have tried to explain the cause of damage to tumors exposed to electrochemical treatment (ECT). In the present study, mammary tissue in adult female rats was treated with constant direct current to investigate the influence of current level, treatment time, and coulomb dosage on tissue destruction. The electrodes used were Pt:Ir (9:1) with spherical tips. Extensive in situ pH measurements were performed with a microcombination glass electrode. Macroscopic examination of treated mammary tissue revealed an almost spherical necrosis with heavy dark color due to the hematin produced during ECT. Histologic examination showed that the direct current induced two different types of necrosis depending on the polarity of the electrode. Steep pH profiles, with pH values switching from nonphysiologic to neutral status within only a few millimeters, were obtained in tissue surrounding the electrodes. Significant differences in lesion sizes and pH profiles were obtained when using a wide range of currents while holding the coulomb dosage constant. The pH at the border of the anodic and cathodic lesions correlated well with certain values, irrespective of current or coulomb dosages delivered. This indicates that in a clinical situation, pH values known to cause total tissue destruction could be used as markers to evaluate the efficacy of treatment.