Objectives: The study examined differential autonomic nervous responses to acupuncture stimulation at the wood points ([Formula: see text]) and the metal points ([Formula: see text]) among the five-shu points of the Pericardium and Triple Energizer Meridian.
Design: This was a crossover study of different acupuncture points with randomized order.
Subjects: The study subjects were 30 healthy female volunteers (22.8 ± 2.6 years old).
Interventions: The acupuncture sessions were carried out over four sessions at 2-5-day intervals at the same time of day with one of the four acupoints: the wood distal point (Zhongchong, PC9), metal distal point (Zhongzhu, TE3), wood proximal point (Jianshi, PC5), and metal proximal point (Guanchong, TE1) on the left hand. After 5 minutes' rest (Pre-Acup), acupuncture needles were inserted, manipulated promptly, and were retained for 20 minutes followed by 5 minutes' rest (Post-Acup).
Main outcome measures: Heart rate variability, skin conductance response, respiration rate, and peripheral skin temperature were measured.
Results: For the normalized low-frequency band of heart rate variability, there was a statistically significant increase during Acup and Post-Acup at the PC9 and TE3 wood points compared with Pre-Acup. Statistically significant decreases for PC5 and TE1 were evident at the metal points. Skin conductance response and peripheral skin temperature, which are indicative of sympathetic activity and blood flow, respectively, were significantly induced at PC9 during Acup compared to Pre-Acup.
Conclusions: The wood points PC9 and TE3 increase sympathetic activity; and the metal points TE1 and PC5 increase the parasympathetic activity. The effect of acupuncture on the autonomic nervous system differs between the wood and the metal points.