[The influence of pressing the meridian course on electroretinogram during acupuncture].

Observation was performed on 23 subjects with marked propagated sensation along meridians (PSM) and 30 without PSM. The electroretinogram (ERG) was recorded with surface electrode and added by an averager. The b wave of ERG evoked by flash stimulation was positive with a latent period about 60 ms and amplitude of 22 +/- 1.66 muv (n = 53). There were 2 types of ERG response during puncturing Hegu (LI 4). The amplitude of ERG b wave increased in 33 subjects and decreased in 20 subjects. However, the acupuncture effect was kept relatively stable in each subject. The spontaneous variation of ERG amplitude was about 10%. In contrast, it changed by 26.5 +/- 2.43% (n = 20) when Hegu (LI 4) was acupunctured alone. It is particularly to be noted that the amplitude of b wave almost remained unchanged, with in the range of 10.08 +/- 2.42% (n = 20), as the pressure was applied on Shousanli (LI 10) during acupuncture, no matter whether the subjects with or without PSM. However, the variation rate of b wave increased by 24.83 +/- 3.74% (n = 15) once again, if the pressure was applied on both side of Shousanli (LI 10), it was nearly equal to the value caused by acupuncture Hegu (LI 4) alone. The contrast between the two is striking. The result revealed again that there may be a certain substantial process advancing along the channel during acupuncture. It is the blockade of this process by mechanical pressure which leads to the decrease of the acupuncture effect.