Objective: To explore the relationship between calcium ion and meridian phenomenon. Methods: A total of 10 female goats (30- 35 kg ) tranquilized by muscular injection of chlorpromazine hydrochloride ( 25 mg ) were used in the present study. Electrical potential values (reflecting the concentration) of Ca

2+ in the tissues at “Ganshu”(BL 18)

“Dachangshu”(BL 25)

“Guanyuanshu” (BL 26) of the Bladder Meridian and 3 control points 3 cm lateral to the abovementioned 3 acupoints were detected by using a needle-type calcium sensor. One minute after insertion of the calcium sensor

the electrical potentials of Ca 2+ in the tissues at “Ganshu”(BL 18)

“Dachangshu”(BL 25)

“Guanyuanshu” (BL 26) of the Bladder Meridian and 3 control points 3 cm lateral to the abovementioned 3 acupoints were detected by using a needle-type calcium sensor. One minute after insertion of the calcium sensor

the electrical potentials of Ca

2+ were determined once every 5 sec

continuous for 3 min . Results: The values of electrical potential of calcium ion in the aforementioned 3 acupoints were all significantly higher than those in the 3 non-acupoints (P

<

0.01 or P

<

0.05)

which suggests an enrichment phenomena of calcium ion in meridian-points. Conclusion: Calcium ion concentration in BL-18

BL-25 and BL-26 is significantly higher than that of non-acupoint

which may be one of the specificities of acupoint. It suggests that the determination of concentration of calcium ion could be regarded as an important physicochemical marker in identifying acupoints.