Background: Acupuncture stimulation and phototherapy have been reported to have analgesic effects and improve the microcirculation. However, few studies have directly examined changes in peripheral blood vessels, either quantitatively or objectively. We assessed the responses of arteriolar blood flow to acupuncture stimulation and phototherapy under direct vision to examine the effects of these treatments.
Methods: We used 40 rabbits with a rabbit ear chamber attached to the auricle. The rabbit ear chamber was fixed to the auricle under a dissecting microscope. Arterioles were selected and observed with the use of a microscope video camera. Pentobarbital was injected IV. The trachea was intubated and spontaneous respiration was maintained. Rabbits were randomly assigned to receive acupuncture stimulation (acupuncture group, n = 10), near-infrared lamp irradiation (lamp group, n = 10), near-infrared low-powered laser irradiation (laser group, n = 10), or no irradiation (control group, n = 10). In the acupuncture group, an acupuncture needle was placed in the auricle for 20 min. The lamp group repeatedly received 1 s of near infrared irradiation (1540 mW) followed by 4 s of treatment cessation. The laser group continuously received 60 mW of laser irradiation. In the lamp and laser groups, the auricle (same site as that of the acupuncture needles in the acupuncture group) was irradiated for 10 min with a contact probe. Arteriolar diameter and blood flow velocity were measured at baseline and for 60 min after acupuncture or irradiation treatment. Blood flow rate was calculated by multiplying the blood flow velocity by the cross-sectional area of the vessels.
Results: Arteriolar diameter significantly increased to 131% +/- 14% in the acupuncture group (P < 0.005), 129% +/- 19% in the lamp group (P < 0.005), and 128% +/- 11% in the laser group (P < 0.005) when compared with the pretreatment value (100%). Maximum values were reached 20 min after the end of the acupuncture stimulation, and 10 min after the end of lamp and laser irradiation. The three groups showed significant increases in arteriolar diameter when compared with the control group (P < 0.005). Blood flow velocity and blood flow rate showed similar trends to arteriolar diameter. Treatment effect persisted for 40-50 min after the end of stimulation and irradiation.
Conclusions: Acupuncture stimulation and phototherapy were directly confirmed to increase the diameter and blood flow velocity of the peripheral arterioles. Acupuncture stimulation and phototherapy, associated with minimal systemic and local side effects, can enhance the microcirculation and may be a useful supportive treatment for diseases caused by poor peripheral blood flow.