Pharmacological analysis of the antiinflammatory effects of low-intensity extremely-high-frequency electromagnetic radiation

Abstract

The anti-inflammatory effect of low-intensity extremely high-frequency electromagnetic radiation (EHF EMR, 42.0 GHz, 0.1 mW/cm2) was compared with the action of the known anti-inflammatory drug sodium diclofenac and the antihistamine clemastine on acute inflammatory reaction in NMRI mice. The local inflammatory reaction was induced by intraplantar injection of zymosan into the left hind paw. Sodium diclofenac in doses of 2, 3, 5, 10, and 20 mg/kg or clemastine in doses of 0.02, 0.1, 0.2, 0.4, and 0.6 mg/kg were injected intraperitoneally 30 min after the initiation of inflammation. The animals were whole-body exposed to EHF EMR for 20 min at 1 h after the initiation of inflammation. The inflammatory reaction was assessed over 3 - 8 h after the initiation by measuring the footpad edema and hyperthermia of the inflamed paw. Sodium diclofenac in doses of 5 - 20 mg/kg reduced the exudative edema on the average by 26% as compared to the control. Hyperthermia of the inflamed paw decreased to 60% as the dose of was increased diclofenac up to 20 mg/kg. EHF EMR reduced both the footpad edema and hyperthermia by about 20%, which was comparable with the effect of a single therapeutic dose of diclofenac (3 - 5 mg/kg). The combined action of diclofenac and the exposure to the EHF EMR caused a partial additive effect. Clemastine in doses of 0.02-0.4 mg/kg it did not cause any significant effects on the exudative edema, but in a dose of 0.6 mg/kg it reduced edema by 14 - 22% by 5 - 8 h after zymosan injection. Clemastine caused a dose-dependent increase in hyperthermia of inflamed paw at doses of 0.02-0.2 mg/kg and did not affect the hyperthermia at doses of 0.4 and 0.6 mg/kg. The combined action of clemastine and EHF EMR exposure caused a dose-dependent abolishment of the anti-inflammatory effect of EHF EMR. The results obtained suggest that both arachidonic acid metabolites and histamine are involved in the realization of anti-inflammatory effects of low-intensity