Effects of acupuncture needle application upon cutaneous microcirculation of rabbit ear lobe

Microcirculatory effects of the application of an acupuncture needle (32-gauge, silver) to the back, corresponding to Geshu (B17) in human beings, were studied in vivo by microscope, using a transparent ear chamber in conscious rabbits. Although no striking findings were obtained during the needle application for a period of 30 minutes, it was clearly observed that the microvascular blood flow increases gradually in parallel with augmenting spontaneous rhythmic fluctuation of the vessel diameter, namely vasomotion, throughout a continuous observation period longer than 2 hours following release from the needle application. Diameters of arterioles and venules at the full-dilating phases of vasomotion reached levels higher than 200% and 250% of the initial values just before application of the needle, respectively. The clinical efficacy of acupuncture was suggested to be explained at least in part by the increased rhythmic microvascular blood flow in parallel with vasomotion, from the physiological point of view based on the previous investigations.