Oxygen

an important substance for metabolism

and its related nitric oxide(NO)and carbon dioxide(CO_2)play a key role in regulating physiological activities.The study on the characteristics of oxygen in the acupoint region has been being conducted for nearly 30 years.In the present paper

the authors review recent development of researches on changes of partial oxygen pressure(PO2)

NO

and CO_2 levels in the acupoint regions.Some researches demonstrated that the PO2

CO_2 and NO contents are relatively higher in some acupoints as Zusanli(ST 36)

etc.in comparison with the neighbor tissues or nonacupoints under normal and pathological states in severe infection patients and rats.After acupuncture stimulation

CO_2 and NO contents were increased

while PO2 content was increased or lowered in some acupoints not in non-acupoints.However

there were also some arguments about the conclusions of acupoint oxygen specificity.In order to verify the results of acupoint oxygen specificity researches

more attentions should be paid to the precise experimental design

repeatable experimental conditions

homogeneity of subjects

human body observation

Deqi effect of acupuncture needle manipulation

etc.in the future studies.