De-qi as an important factor to therapeutic effect of acupuncture for years, It's a concrete pathway to approach Qi, an abstract concept in Chinese medicine. However, all previous physicians and medical scientists have different interpretation to De-qi, and no objective principles for clinical practice, teaching and studies.

Qi propagated combined with acupuncture practice always be seen as De-qi , therefore, the study control "transmission or not" and "direction of sensation propagated" to compare what's different in human body. If the change happened as prediction based on acupuncture theories, it could define De-qi for operation.

The study will collect 60 subjects, from age 20 to 40, the same numbers of male and female. They will accept different manipulation in left hand HeGu(LI4), and assessed the variations in microcirculation, temperature of left forearm, and waxing/waning of yin-yang , Qi and blood in related meridian. We hope to understand if sensation propagated is primary factor of De-Qi and acupuncture effect .

Inclusion Criteria:

• both male and female
• age:20-40 years old

Exclusion Criteria:

• to be afraid of acupuncture
• easily fainting
• right index finger has been injured recent one month
• had taken drugs can trigger vasodilatation or vasoconstriction recent three months
• systemic diseases
• pregnancy