Local atomic structure in acupuncture points studied by Fe K-edge EXAFS

D. M. Zhang X. Y. Zhang

Department of Physics, Fudan University, Shanghai 200433, China

Abstract: In this work, Extended X-ray Absorption Fine Structure (EXAFS) of Fe K-edge was used to investigate the Fe local atomic structures of acupuncture points (acupoints) and non-acupoints of human beings. The EXAFS spectra of acupoints samples of Guanyuan, Neiguan and Sanyinjiao were collected at BL13B of Photo Factory (PF) of High Energy Accelerator Research Organization, Japan. Not only did we find that the Fe-O mean coordination numbers were obviously different between acupoints and non-acupoints, but also we found that the Fe-O and Fe-N bonds length increased in those samples from acupoints to non-acupoints. With the increase of Fe-N bond length of non-acupionts, the ability of transporting oxygen decreases. As a result of the change of Fe-O coordination number and the Fe-O bond length from acupoints to non-acupoints, there must be a close relationship between the N-Fe-O combinative structure and the difference of obvious structure and function in and out of acupoints.

MotivationThe underlying anatomy and physiology of Traditional Chinese meridian theory and acupuncture technique have not been characterized.Fe is one of the most abunda1nt metals and plays a very important role in humans.EXAFS is a very powerful tool for probing local atomic structures because of its element selectivity and independence of long-range order of materials.

EXAFS model

haemoglobin FeCl2

Samples Bonds N

GY_MU4_in Fe － N 5 2.036± 0.006 0.063± 0.008 -9.25± 0.91

Fe － O 0.94±0.18 1.881± 0.025 0.012± 0.036 0.75± 1.41

GY_MU4_out Fe － N 5 2.027± 0.008 0.095± 0.007 -13.22± 0.87

Fe － O 1.414± 0.182 1.937± 0.011 0.051± 0.016 -5.175± 1.672

NG_MU4_in Fe － N 5 2.015± 0.004 0.084± 0.007 -11.45± 2.14

Fe － O 0.737± 0.213 1.997± 0.028 0.123± 0.023 9.403± 2.747

NG_MU4_out Fe － N 5 2.058± 0.005 0.084± 0.005 -7.725± 0.749

Fe － O 1.455± 0.328 2.011± 0.012 0.090± 0.012 9.587± 1.27

SYJ_SK1_in Fe － N 5 2.005± 0.004 0.061± 0.015 -12.73± 2.48

Fe － O 0.555± 0.133 1.797± 0.018 0.01± 0.06 -12.20± 3.57

SYJ_SK1_out Fe － N 5 2.092± 0.016 0.010± 0.004 1.090± 0.589

Fe － O 2.464± 0.246 2.485± 0.009 0.083± 0.013 -0.081± 1.395

Fitting curves

ConlusionThe ability of transporting oxygen in acupoints is much stronger than that in non-acupoints[1].There must be a closely relationship between N-Fe-O combinative structure and the difference of obvious function in and out of acupoints, this is mainly because of the differences of N-Fe-O combinative structure in micro-vessel.[1] Zhonghua Wu, et al., EXAFS study on the local atomic structures around iron in glycosylated haemoglobin. Phys. Med. Biol. 2001 46 N71-N77.