Photoluminescence of acupoint “Waiqiu” in human superficial fascia

The spectral characters of an acupuncture point named “Waiqiu” in superficial fascia tissue have been studied by photoluminescence (PL) spectroscopy under the excitation of 457.9 nm. The PL around “Waiqiu” acupuncture point consists of two sub-bands resulting from the flavin adenine dinucleotide (FAD) and phospholipids, and the porphyrins (including purine, isoxanthopterin and tryptophan), respectively. More emission due to FAD and phospholipids is found inside the acupuncture effect area of “Waiqiu” than its marginal or outside acupuncture regions. The ratio of emission intensity of FAD and phospholipids to one of porphyrins gradually decreases along the direction away from the center of the acupuncture point. It implies that the component proportion changes between FAD, phospholipids and porphyrins around the “Waiqiu” acupuncture point. We suggest that there might be a certain relationship between redox function of FAD and “Waiqiu” acupuncture effect.