Negative ions accumulating at the positive pole or anode produce an acidic reaction through the formation of hydrochloric acid and produce softening of the tissues by decreasing protein density which is useful in treating scars or adhesions.
Positive ions that accumulate at the negative pole produce an alkaline reaction with the formation of sodium hydroxide and produce hardening of the tissues by increasing protein density.
Making the tissue either alkaline or acidic can have a devastating effect on microbes and parasites. Too bad you didn't know you could do this with 9 volt batteries in series. Much cheaper. Direct current treatments were one of the very first electro-medicine treatments and they were so effective that most doctors had DC treatment devices in their office. Then the FDA was formed and they started promoting/defending pharmaceutical remedies and black-balled electro-mendicine so that it quickly vanished from the American scene.