The Na/Ca Exchange as a Target for Antitumor Effect of 4Hz Pulsing Magnetic Field.

The correlation between cell hydration and proliferation is one of the controversial subjects in the present cancer research because the detailed mechanism(s) of correlation between these two cell parameters are not evaluated yet. The fact that magnetic fields have antitumor effects and our previous data that the effect of 4 Hz pulsing magnetic field (PMF) is realized by the activation of Cyclic guanosine monophosphate (cGMP)-dependent Na/Ca exchange allow us to suggest that through the study of PMF effects on cell hydration and proliferation in soft tissues of sarcoma-180 tumor-carrying mice compared with those of healthy ones will be possible to evaluate the character of correlation between cell hydration and proliferation in norm and pathology. The daily 30-min PMF (0.2 mT) exposed on tumor-carrying mice has lifetime prolongation, time-dependent depression of tumor growth, decrease of thermal threshold, and lactate concentration in blood. In the initial (6 days) period tumorigenesis PMF leads to dehydration in spleen cells, which is accompanied by the activation of cell proliferation, while in late periods of tumorigenesis it leads to cell hydration accompanied with proliferation. We are suggesting that PMF-induced overhydration and the increase of cell proliferation in cancer tissue as a consequence of high [Ca]i-induced activation of Ca-calmoduline-NO-cGMP pathway leads to the activation of FNa/Ca exchange, while its antitumor effect expressed in initial period of tumorigenesis is due to the activation of cGMP-dependent FNa/Ca, where because of low [Ca]i, it brings to cell dehydration as a result of reactivation of Na/K pump.