COMPARISONS OF PAIN RELIEF MECHANISMS BETWEEN NEEDLING TO THE MUSCLE,STATIC MAGNETIC-FIELD, EXTERNAL QIGONG AND NEEDLING TO THE ACUPUNCTURE POINT

Pain relief mechanisms of needling to the pain-producing muscle, appli cation of a static magnetic field ol external qigong, and needling to the acupuncture point were investigated in an experimentally designed pain producing muscle of animals. Single isometric twitch height in si tu was reduced gradually by 10 Hz tetanic stimulation for one hour of the gastrocnemius muscle of guinea pigs. This reduction of twitch heig ht was recovered by injection of 0.3-1 mi saline to the artery of this muscle, or of injection of a vasodilator, isoproterenol dissolved in 0.1 mi saline. Hence, reduction of twitch height could be induced by r eduction of circulation in the muscle and recovery of it could be indu ced by recovery of circulation. Since it is easily considered that a p ain substance might be accumulated in a muscle under reduced circulati on, and such an accumulated substance might be eliminated by recovery of circulation, the reduction of twitch height after tetanic stimulati on could be estimated as the pain-producing muscle and recovery of twi tch, as the pain relieving muscle. 1) Needling to the pain muscle, 2) application of a static magnetic field or external qigong to the muscl e, and 3) needling to the acupuncture point recovered the reduced twit ch height due to tetanic stimulation. Atropine abolished this effect i nduced by the above 1, 2 and 3 procedures. Hence, the cholinergic vaso dilator nerve might be involved in the induction of this effect. A sci atic nerve cut did not influence the effect of 1), but abolished the e ffect of 3), Denervation and capsaicin abolished the effect of 1). Sub stance P and a calcitonin gene- related peptide (CGRP) recovered the r educed twitch height, and atropine blocked the effect of CGRP, but did not block that of substance P. The effect of 2) was equivalent to tha t of anticholinesterase. A rostral lesion of the contralateral anterio r hypothalamus did not abolish the effect of 3, but a caudal lesion of this region did. Electrical stimulation of this region produced an ef fect similar to that of 3). From these results, it was concluded that muscle pain relief by these procedures might be induced by recovery of circulation due to the enhanced release of acetylcholine as a result of activation of the cholinergic vasodilator nerve endings innervated to the muscle artery. However, manners of activation of the cholinergi c nerve were different in effects of 1), 2) and 3). 1) might be induce d by axon reflex of the CGRP nerve, 2) might be induced by inhibition of cholinesterase and 3) might be induced by a somato-autonomic reflex . The reflex center of this might be in the anterior hypothalamus.