Abstract
OBJECTIVE: Increments of local blood flow and vasodilatation induced by acupuncture (acp) and moxibustion (mox) 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 mechanical or heat pain threshold of the skin and axon reflex induced by acup and mox were examined. METHODS: Sixteen healthy volunteers with informed consent (32 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 acupuncture (diameter 240 μ m) or an indirect moxibustion (peak temperature was about 50 degree, Kamaya Co. Ltd, Japan), and the vasodilatation was measured by blood flow meter. A piece of anesthetic (lidocaine 18 mg) or sham patch (30.5 × 50 mm) was applied to the skin surface where pain tests and blood flow measurements were done. RESULTS: Mechanical (pin-prick) pain threshold was significantly reduced (P<0.01, Wilcoxon t-test) 60 min after the application of anesthetic patch, whereas, thermal pain threshold and flare reactions produced by both acp and mox did not change. CONCLUSION: The facts that acp and/or mox induced flare reactions were not blocked by the lidocaine application, might suggest the involvement of lidocaine-insensitive and heat sensitive afferents and/or receptors channels in the signal transduction processes of acp and mox stimulation. [J Physiol Sci. 2008;58 Suppl:S175]
