A segmental effect involved in the changes of skin blood flow induced by acupuncture in normal health human

Our previous studies found that segmental effect of spinal nerve plays an important role in acupuncture stimulation (AS) on nail-fold microcirculation. Calcitonin-gene related peptide (CGRP) is a potent endogenous vasodilator. Therefore, the aim of the present study was to investigate the effect of AS on skin blood flow (SBF) and skin temperature (ST), and the involvement of spinal nerve segment and CGRP. A total of 17 healthy adult volunteers were studied, and all of them accepted three assessments as follows: (1) left Waiguan (SJ5) assessment (LW), AS applied to Waiguan acupoint of the left hand with obtaining qi; (2) right Waiguan assessment (RW), AS applied to Waiguan acupoint of the right hand with obtaining qi; (3) sham assessment, AS applied to the cutaneous portion of Waiguan acupoint of the left hand only. Each assessment was divided into before acupuncture period (BP), acupuncture period (AP) and post acupuncture period (PP). Both SBF and skin temperature (ST) were recorded simultaneously for 20 min at central dorsal part of the left hand in each period. Besides, the levels of CGRP in the blood were measured before AS, and at 20 min after AS in the LW assessment. Results indicated that the SBF was less in the PP than that in the BP, but SBF did not significantly vary between AP and BP, and between AP and PP in the LW assessment; SBF is similar among BP, AP, and PP in the sham and RW assessments; the difference of SBF between AP and BP was greater in the LW assessment than that in the sham assessment; the difference of SBF between AP and BP, and between PP and BP was greater in the LW assessment than that in the RW assessment. The levels of CGRP in the BP were similar to that at 20 min after AS; ST was similar among BP, AP and PP in the sham, LW and RW assessments. These results suggested that a segmental effect of spinal nerve is involved in the changes of SBF induced by AS since both the cutaneous part of left Waiguan acupoint and central dorsal part of the left hand belong to the 7th segment of cervical nerve.