Needling non-acupoints that lie on an acupuncture channel has a stronger effect on blood perfusion (BP) in the surrounding tissue than needling non-acupoints that do not line on a channel. Chinese investigators enrolled 20 healthy volunteers in their experiment and performed acupuncture at two selected points on each participant. One point was located two centimetres above Chengshan BL-57 on the line of the Bladder channel. The other point needled was at the same level as Chengshan BL-57, but two centimetres lateral to the Bladder channel. The results showed that BP around Chengshan BL-57 was significantly higher after acupuncture at the non-acupoint on the channel than after acupuncture at the point off the channel. The findings of this study support those of previous research which suggest that acupuncture channels represent lines of low hydraulic resistance along which interstitial fluid can flow, allowing transport of histamine, substance P and other intercellular signalling chemicals.