Acupuncture therapy developed in China over several thousand years (15). It is based on a philosophy in which "life energy" called ch'i is viewed as composed of two fundamentally opposing aspects: yin, the passive, negative principle and yang, the active, positive principle. Good health, which in the holistic Chinese view includes both physical and mental health, depends on the maintenance of a harmonious equilibrium between yin and yang, together with unimpeded circulation of ch'i throughout the body via 14 channels known as meridians: Imbalance or obstruction in the flow of the ch'i is manifested as illness. Health can be restored by rectifying the imbalance via stimulation applied at one or more specific locations on the meridians called acupuncture points. The particular points to be treated are chosen after an examination of the patient and an evaluation of his symptoms. Originally, treatment was by manual rotation of fine gold or silver needles inserted at the points. More recently, a variety of electrical signals (electroacupuncture) have been used instead of manual stimulation (16, 17). At present acupuncture and electroacupuncture are used in China, primarily to treat pain and neurological disorders (16).

The earliest known Chinese treatise on acupuncture therapy dates back to about 500 B.C., and the system it describes has remained essentially unchanged since then (15). Acupuncture was introduced in the West in the seventeenth century, and interest in it was rekindled by the new contacts with mainland China in the early 1970's. This resurgence of interest has led to numerous studies of the clinical efficacy of acupuncture as well as basic laboratory studies of its physiological basis and mode of action. Acupuncture has been reported to be effective in providing pain relief (18), and many hypotheses have been proposed to explain the effects resulting from acupuncture treatment (18, 19).

The most basic question concerning acupuncture is whether there is a physical basis for the system of points and meridians. Such a foundation would provide a potential explanation for the reported effects as well as a logical framework for further studies. Otherwise, one would be left only with theories based on hypothesis or suggestion. Attempts to correlate the acupuncture meridians and points with the human nervous system have been inconclusive: some investigators have claimed that many acupuncture points correspond to known concentrations of sensory receptors (20), while others see no relationship to the anatomy of the peripheral nervous system (21). There have been suggestions that acupuncture points are distinguishable by their lower DC electrical resistance (22), but others have said that this phenomenon is largely due to experimental artifact caused by exertion of greater pressure on the measuring instrument over the sites of supposed acupuncture points (23).

Our interest in acupuncture arose out of the concept of the electrical control system regulating growth and healing (chapter 2). Such a system would receive and transmit signals that indicated the occurrence of injury. Injury signals are usually equated with the perception of pain, but pain may be merely the consciously perceived portion: the major portion may be addressed to the integration areas that govern the DC system where it would elicit an appropriate output electrical signal, directed towards the area of trauma, that would produce the cellular stimulation necessary to initiate healing. Since the relief of pain is a major effect produced by acupuncture, we theorized that the points and meridians might play a role in the DC control system (35). If so, they should have electrical characteristics that differ from control points. We undertook a series of controlled laboratory measurements to study this possibility.

Using a system designed to exclude pressure artifacts, we found that approximately one-half of the points measured were local resistance minimal when compared to the surrounding tissue (24, 25) (Fig. 11.1). In later studies, we found that AC impedance also differed: the equivalent series resistance between acupuncture points was lower than between control points (26), while the equivalent capacitance was higher (27). Furthermore, the resistance between two meridian (but not acupuncture) points was lower than that between two control points (28). Thus, both acupuncture points and meridians exhibited electrical characteristics that differed from those of control points.


Fig. 11.1. Electrical characteristics of acupuncture points. A total of 17 acupuncture points on the large intestine (Li) and pericardium (P) meridians were measured (24). The mean and standard deviations of the percent increase in conductance (the reciprocal of DC resistance) for each acupuncture point for the 7 subjects tested are shown. The dotted line indicates the overall mean percent increase at the control points. Acupuncture points Li-2, Li-4, Li-5, P-7 and P-8 were significant local maxima (resistance minimal) for all 7 subjects. Points Li-6, Li-7, Li-8, Li-11, Li-12, P-3, P-4 and P-6 were significant local maxima for at least 5 of 7 subjects.


A growing body of evidence implicates endorphins (endogenous morphine-like substances) in acupuncture analgesia. Sjolund and Eriksson found that intravenous injection of naloxone (an opiate antagonist) in human subjects resulted in a return of pain sensation after analgesia had previously been achieved by low-frequency electroacupuncture, thereby suggesting that the analgesia was mediated by the release of endorphins (29, 30). Pomeranz and colleagues reported that low-frequency electroacupuncture induced analgesia in mice that could be blocked by naloxone, again indicating that low-frequency stimulation produced analgesia via a release of endorphins (31-34).

At present, two points have been clearly established: first, the classical acupuncture system, at least in part, has unique electrical characteristics which establish its objective physiological reality; and second, electroacupuncture induces analgesia by stimulating release of endorphins, the body's naturally produced analgesics. Although many other points remain unresolved, acupuncture seems clearly to be a fruitful field for further research; it offers the possibility of considerable rewards in both basic-science and clinical areas.

Chapter 11 Index