[Dense innervation of acupoints and its easier reflex excitatory character in rats].

Objective: To study the innervating character of tissues around the acupoints and along the meridian course and to analyze the reflex activity correlation between acupuncture points in a given meridian in the rat.

Methods: Forty Wistar and 15 SD rats were used in this study. Electrical activities of microfilaments of the afferent nerves (deep tibial nerve, peroneal nerve and the lateral cutaneous nerve of the leg) were observed for identifying their receptive field and the type of nerve fibers. Nerve stem-antidromic stimulation induced Evan's blue extravasation method was employed to compare the difference of the nerve ending distribution in the acupoint area and non-acupoint area. The reflex activities evoked by electric stimulation of the acupoint were used to analyze the interrelation between acupoint and meridian.

Results: Findings showed that a great majority of the afferent nerve endings supplying the tibialis anterior/rectus femoris muscle and the foot skin distributed in an uneven pattern in the sites being in accord with acupoints or with the orbit of meridians. Antidromic stimulation of C-fibers in the deep tibial nerve evoked extravasation of Evan's blue from the plasma into the interstitial fluid, blue foci appeared at the acupoints of the Stomach Meridian and along the orbit of the Stomach Meridian. The special distribution of the afferent nerve endings in the acupoint was also associated with the special reflex activity originating from the acupoints of the muscle group of a given meridian.

Conclusion: The acupoint is an excitable muscle/skin-nerve complex with greatest concentration of nerve endings. The meridian consists of acupoints that possess a close interaction in physiological reflex activities.