Objective To observe the effect of electroacupuncture(EA)stimulation of different acupoints at the distal ends of the limbs on cardiac function in volunteers with acute hypoxia

so as to determine if its actions are realized by way of segmental innervations or meridians.Methods Twenty healthy volunteers were divided into control

Quze(PC 3)

Shousanli(LI 10)

Guangming(GB 37)and Zusanli(ST 36)groups(both PC 3and LI 10 are innervated by spinal C3-C6

and both ST 36 and GB 37 innervated by L5-S1).Acute hyoxia(simulating the conditions of about 5 000 mheight above the sea level)was induced by asking the volunteers to inhale low-oxygen gas mixture(10.8% O2+ 89.2% N2)for 30 min

when

the participants' cardiac output(CO)

heart rate(HR)

left cardiac work(LCW)

left ventricular ejection time(LVET)were measured using a ICG Monitor and EA stimulation(10Hz/20 Hz

1-2V)was also conducted for 20 min following inhaling low-oxygen for 10 min.Results Before low-oxygen inhale

the levels of CO

HR

LCW and LVET ratios(test value/basic value)of the control

PC 3

LI 10

ST 36 and GB 37 groups were comparable(P>0.05).After inhaling low-oxygen gas mixture for 10 min

the levels of CO

HR

and LCW ratios were significantly increased

and the LVET ratios were notably decreased in the five groups(P<0.05).Compared with the 10min-low-oxygen inhale of the same one group

CO and HR ratios at both EA 10 min and 20 min in the PC 3and ST 36 groups

LCW ratios at EA 10 min in both PC 3and ST 36 groups were notably down-regulated(P<0.05)

while the LVET ratios of both PC 3and ST 36 groups was significantly prolonged(P<0.05).No significant changes of CO

HR

LCW and LVET ratios were found in the LI 10 and GB 37 groups after EA for 10 min and 20min(P>0.05).Conclusion EA stimulation of Quze(PC 3)and Zusanli(ST 36)

but not Shousanli(LI 10)and Guangming(GB 37)can lower CO

HR and LCW levels and increase LVET in volunteer subjects undergoing acute hypoxia

suggesting that the therapeutic effect of EA maybe not rely on the segmental innervations

but rather

depend on the meridians to which the acupoints belong.