Some reports showed that pressing the meridian travelling course could decrease the effect of acupuncture in subjects with or without propagated sensation along meridians (PSM). Can pressing the meridian travelling course affect the variation of oxygen partial pressure (PO 2) in deep tissues along the meridian during acupuncture? To solve this problem

thirty healthy volunteers without PSM were subjected into this observation. Three points of the Large Intestine Meridian were selected

and a medial and a lateral point 2 cm from each measured point were taken as the control sites. One hundred and twenty times of observation were performed

the results showed:(1) the measured points decreased during puncturing Hegu (LI 4)

while the PO 2 in the points of the meridian decreased more remarkably than that in control sites; (2)when the pressure was applied to the meridian travelling course

the variation rate of PO 2 in the points along the meridian decreased obviously (P<0.05)

but there were no any marked changes in the control sites; (3) the difference of the variation rate of PO 2 between the pressed point and non pressed point was significant when the pressure was applied to the meridian travelling course. If the pressure was applied to the control sites beside the meridian course

the above mentioned results were not found. The results support the suggestion that there may be a certain substantial advancing process along the meridian course during acupuncture. It is thus possible that when blocking this process by mechanical pressure

the effect of acupuncture stimulation will be poor.