Interferential therapy produces antinociception during application in various models of inflammatory pain.
OBJECTIVE
Although interferential therapy (IFT) is used widely in the management of many painful conditions, the effectiveness and the mechanism of action of IFT in animal models of inflammatory pain have not been evaluated. The aim of this study was to evaluate the effectiveness of IFT in reducing inflammatory pain and edema in rats.


METHODS
Sixty-nine male Wistar rats were used in the study.


METHODS
The effect of IFT application (4,000-Hz carrier frequency, 140-Hz amplitude-modulated beat frequency, pulse duration=125 milliseconds, current intensity=5 mA) for 1 hour on the formalin-induced nociceptive response and edema and on carrageenan-induced mechanical hyperalgesia and edema was evaluated.


RESULTS
Interferential therapy significantly reduced the formalin-evoked nociceptive response when applied to the paw immediately after but not before the formalin injection. Interferential therapy application at 2 hours after the carrageenan injection significantly prevented a further increase in carrageenan-induced mechanical hyperalgesia only immediately after discontinuation of the electrical current application. The antinociception induced by IFT was not attributable to a reduction in inflammation because IFT did not significantly reduce the edema induced by either formalin or carrageenan.


CONCLUSIONS
The results suggest that, despite its short-duration effect, IFT is effective in reducing inflammatory pain and should be considered primarily for use in the control of acute inflammatory pain.
Jorge
Sérgio
S
Department of Physiology, Faculty of Dentistry, University of Campinas, Piracicaba, São Paulo, Brazil.
Parada
Carlos A
CA
Ferreira
Sérgio H
SH
Tambeli
Cláudia H
CH
D000818:Animals; D002351:Carrageenan / Q000494:pharmacology; D004195:Disease Models, Animal; D004487:Edema / Q000517:prevention & control*; D005404:Fixatives; D005557:Formaldehyde; D006930:Hyperalgesia / Q000139:chemically induced / Q000517:prevention & control; D007249:Inflammation / Q000517:prevention & control*; D008297:Male; D009619:Nociceptors; D010146:Pain / Q000517:prevention & control*; D010147:Pain Measurement; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D004561:Transcutaneous Electric Nerve Stimulation / Q000379:methods*
D005404:Fixatives; D005557:Formaldehyde; D002351:Carrageenan