We found that the skin lower impedance points in animals indicated the locations of meridian points. We wondered if they have specificity funct- ionally. Recently

laser has been employed in medical treatment and acu- puncture

but saiely used in experimental acupuncture rescarch. This pap- er was aimed to observe the effects of low-energy He-Ne laser irradiation of "Neiguan" on ECG in cats and to determine the functional specificity of "Neiguan" localized by lower impedance.the preliminary study of the relation between the laser offects and some nerves was also reported. Methods The standard lead of ECG and respiration were recorded at 15 min. int- ervals in anesthetized cats. "Neiguan" was localized by lower impedance. Stimulation was not given until the heart rate respiration and tend were steady. He-Ne laser with 6328A wave length

3mW output

20mm distance

1 mm beam diameter was used for 15 min irradiation of "Neiguan" on each side or control point. In some animals

5-30Hz or 5-1000Hz electro-acupun- ture lasting 30 min

was applied. In the control group

the procedures we- re the same but no stimulation was given. ECG parameters were measured in 23 cats before stimulation. Results 1.ECG parameters in anesthetized cats were presented. 2.In the control group of 10 cats

ECG showed little change during the period of the ewperiment. Laser irradiation or 5-1000Hz electro-acupunc- ture resulted in decresing of heart rate (HR) in the majority of cats whi- le R wave and T wave enlarged in some of them. 5-30H_2 electro-acupunc- ture mainly caused HR increasing. The alteration of HR began in 15 min. or 30 min.after stimulation. Frequently

it lasted to the end of experim- ents and did not turn back to the previous range. 3.Self control experiments were carried out int in 10 cats. Each cat was tested twice by random order either by stimulation of the lower impedan- ce point within "Neiguan" area or the adjacent point 5mm away laterally. The HR effect showed difference statistically between two groups of exp- eriments. 4.After laser irradiating "Neiguan" in 9 cats which showed depressing of HR

the median nerves were bilaterally cut. When the stimulation was repeated

no significant HR effect could be seen. Laser irradiation of the central end of the cut median nerves in 10 cats gave similar HR effects to that of irradiating of "Neiguan". 5.After the cervical vagi were bilaterally cut in 9 cats

ECG effects fo- llowing laser stimulation appeared no definite difference from those with intact vagi. In conclusion

Low-energy He-Ne laser irradiation of "Neiguan" affected the heart rate and R wave of ECG in cats. It seemed that these effects were transmitted by median nerves but not the cervical vagi

and humoral factors were probably involved in the process. We consider thet the skin lower impedance points show specific relation to the nature of meridian points and low-energy laser irradiation is superior to electro-acupuncture in acupuncture research.