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
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