[Effect of acupoints with different tissue on electroacupuncture sensation]

To evaluate the influence on frequency, intensity and the amount of current flow produced by electroacupuncture sensation of acupoints with different distributions (meridian category, tissue type and nerve innervations).

Twenty-one healthy volunteers were enrolled. According to the different tissue of acupoints, paired acupoints were grouped: Zusanli (ST 36) vs Yanglingquan (GB 34) (different meridian categories), Neiguan (PC 6) vs Daling (PC 7) (different tissue types), Zusanli (ST 36) vs Shuidao (ST 28) (different nerve innervations), Guanyuan (CV 4) vs Zhongwan (CV 12) (different nerve innervations), and Zusanli (ST 36) vs Guanyuan (CV 4) (different meridian categories, tissue types and nerve innervations). The electric frequency was 15 Hz. The electric current was under the participant's tolerance without sharp pain; the electroacupuncture was applied for three times with interval, 90 seconds totally. Soreness, numbness, fullness, heaviness, tingling, pressure, dull pain, warmness, coolness and amount of current flow were recorded, and the frequency, intensity and current amount between the paired acupoints were compared.

There were no significant differences in frequency of needling sensations between paired points (all P > 0.05). In the 9 electroacupuncture sensations, fullness, numbness and soreness were most commonly seen and obvious, heaviness, pressure and tingling came second, and dull pain, warmness, and coolness occurred at lower frequency. There were differences in the intensity of acupuncture sensation between paired acupoints in part of them, the soreness, fullness and heaviness at Zusanli (ST 36) were stronger than those at Shuidao (ST 28) (all P < 0.05 ); fullness and numbness at Zusanli (ST 36) were stronger than those at Guanyuan (CV 4) (both P < 0.01); fullness at Guanyuan (CV 4) was stronger than that at Zhongwan (CV 12) (P < 0.05 ); the current flow of electroacupuncture was similar between paired acupoints (all P > 0.05).

In the situation that there is no obvious difference in amount of current flow caused by electroacu puncture sensation, the obvious correlations between frequency of electroacupuncture sensation and tissue properties of acupoints are not appeared, and the difference of sensation intensity between paired acupoints may be associated with different nerve innervations. The frequency and intensity of electroacupuncture sensation at one acupoint are stable at different times.