Effects of extremely-low-frequency pulsed electromagnetic fields on collagen synthesis in rat skin.

To investigate the effects of extremely-low-frequency PEMFs (pulsed electromagnetic fields) on the synthesis of epidermal collagen, six groups of animals each consisting of eight mature male rats were selected randomly: one group for the control and five for the test. Using a parallel set of Helmholtz coils, a uniform field intensity of 2 mT at different frequencies of 25, 50 and 100 Hz yielded the most effective frequency to be 25 Hz. Then, at this frequency, two different field intensities of 1 and 4 mT were applied. The treatment time of 2.5 h/day lasted for 8 days, keeping the same procedure for the control group, except with the field turned off. On the ninth day, the rats were killed and skin samples from the dorsal region were taken for collagen assessment by measuring hydroxyproline content using the Stegemann-Stalder [(1967) Clin. Chim. Acta 8, 267-273] method. The results indicated that a PEMF of 2 mT at 25 Hz increased the collagen synthesis (P < 0.05). The other intensities and frequency setting did not have any noticeable effect; however, at a frequency of 25 Hz at 4 mT, collagen increase was also noticed. It was concluded that at 25 Hz under a field setting of 2 mT for the duration of 8 days, stimulation of skin at 2.5 h/day would cause increase in collagen synthesis in rat skin.