Objective To investigate the functional specificity of acupoint by means of acupoint injection of Dobutamine Hydrochloride (DH). Methods Male SD rats were randomized into normal control (NC)

EA-Neiguan (PC 6)+acupoint injection (AI

EA-PC 6+AI)

EA-Zusanli (ST 36)+AI (EA-ST 36+AI)

and EA-intramuscular injection site (IMIS)+intramuscular injection (EA-IMIS+IMI) groups

with 8 rats being in each group. EA (2 Hz/15 Hz

3 mA) was applied to bilateral "Neiguan" (PC 6)

"Zusanli " (ST 36) and muscular-injection site for 10 min. DH (a β1-adrenoceptor agonist) solution (100 μg/kg) was injected intramuscularly into the gluteus maximus after termination of EA intervention. The left ventricular systolic pressure (LVSP)

heart rate (HR) and +dp/dt max were recorded before and 2

5

15 and 30 min after injection of DH. Results The values of LVSP

HR and +dp/dt max in EA-PC 6+AI group were significantly higher than those in NC

EA-ST 36+AI

and EA-IMIS+IMI groups (P<0.01) 2 and 5 minutes after EA plus acupoint injection of DH. No significant differences were found between EA-ST 36+AI and EA-IMIS+IMI groups in LVSP

HR and +dp/dt max (P>0.05). After injection of DH for 30 minutes

the values of LVSP

HR and +dp/dt max in EA-PC 6+AI group were still significantly higher than those in NC group (P<0.01). Conclusion EA-PC 6+AI DH is significantly superior to EA-ST 36+AI DH and EA-IMIS+IMI DH in producing a stronger cardiac excitatory effect and a longer post-effect

showing a relative specificity of the acupoint in upregulating cardiac functional activities.