INDUCTION OF SISTER-CHROMATID EXCHANGES BY MODULATED, LOW-FREQUENCY ELECTRIC-FIELDS IN FIBROBLASTS FROM NORMAL DONORS AND FROM PATIENTS WITH XERODERMA-PIGMENTOSUM AND DYSPLASTIC NEVUS SYNDROME

The following paper summarizes experiments carried out to find the eff ects of electric fields which are used in therapeutic applications (e. g. muscle stimulation, analgesia etc.). Human fibroblasts derived from normal donors, as well as from patients with xeroderma pigmentosum (X P) or dysplastic nevus syndrome (DNS) were exposed, in vitro, to weak electric 4,000 Hz fields, amplitude modulated 25 and 50 Hz, respective ly. The treatment increased the rate of sister chromatid exchanges (SC E) to above the spontaneous level in all fibroblast types. The maximum effect was found for XP-cells at a field strength of 1 V/m (50 Hz). H owever the increase of SCE was not high as in comparable experiments w ith nocives, e.g. UV-light. A large increase (4 times higher) in field intensity did not result in higher SCE rates and even lowered the res ponse at 50 Hz. No differences were observed between the different typ es with the exception of a slightly higher responsiveness of the XP-fi broblasts at the lower field intensity. Variance analysis revealed sta tistically significant relationships for the dependence of SCE-inducti on upon field amplitude and for the interaction between amplitude and modulation frequency.