Abstract
OBJECTIVE: Increments of local blood flow and vasodilatation induced by acupuncture and moxibustion have been known as axon reflex of unmyelinated afferent fiber receptors such as polymodal receptors. In this study, effects of application of local anesthetic patch on pain threshold of the skin and axon reflex induced by moxibustion were examined. METHODS: Five healthy volunteers with informed consent (ten forearms allocated anesthetic or sham group, double blinded manner) were used and pin-prick pain and heat pain thresholds were measured. The flare reactions were induced by the Kamaya-mini (Kamaya Co.Ltd, Japan), a kind of indirect moxibustion (peak temperature was about 50°C), and the vasodilatation was measured by blood flow meter. A piece of anesthetic (lidocaine 18mg) or sham patch (30.5 x 50 mm) was applied to the skin surface where pain tests and blood flow measurements were done. RESULTS: The mechanical pain threshold (pin-prick) and local blood flow response were significantly reduced (P<0.05, Wilcoxon t-test) 60 min after the application of anesthetic patch, but the heat pain threshold did not change. CONCLUSION: In this study, the flare reaction evoked by moxibustion was blocked by local anesthetic patch without changing heat pain threshold. These results suggest that lidocaine insensitive type receptors might be involved in the signal transduction mechanism of moxibustion, and also suggest that the thermal sensation provoked by moxibustion was conducted through unmyelinated peptidergic fibers such as the polymodal type receptors. [J Physiol Sci. 2006;56 Suppl:S180]
