Objective: To explore the relationship between the effect of electroacupuncture (EA) and EA of different layer tissues of the acupoint area and different acupoints in upregulating mean arterial pressure (MAP) and heart rate (HR) in hypotension plus bradycardia rats.
Methods: A total of 200 SD rats were used in the present study. Bradycardia plus hypotension model was established by intravenous injection of 0.4% propranolol (0.4 mg/100 g, maintaining dosage 0.025 mg/100 g per minute). EA (2 Hz/15 Hz, 5 mA) was applied to (1) right "Daling" (PC7) and "Jiexi" (ST 41), "Ximen" (PC 4) and "Housanli" (ST 36), "Quze" (PC 3) and "Dubi" (ST 35) which have a similar tissue structure, and are located in the upper and lower limbs and different meridians, and non-acupoint [3 mm left-superior to the "Tianshu" (ST 25)], (2) skin, muscle layer and periosteum part of "Ximen" (PC4), (3) skin, muscle layer and periosteum of "Housanli" (ST36) for 15 min. The HR and MAP were recorded by using a multi-channel physiological signal sampling-processing system.
Results: (1) In comparison with the model group, the percentages of the increased HR and MAP in the "Ximen" (PC4), "Quze" (PC3), "Housanli" (ST 36) and "Jiexi" (ST41) groups, PC 4-skin, PC 4-muscle, PC 4-periosteum, ST 36-skin, ST 36-muscle and ST 36 periosteum groups, and the increased HR in the "Dubi" (ST 35) group were upregulated significantly (P < 0.05, P < 0.01). The percentages of the increased HR and MAP were significantly higher in the "Quze" (PC3) and "Ximen" (PC4) groups than in the "Daling" (PC7) group (P < 0.01), and the increased HR evidently higher in the "Housanli" (ST36) and "Jiexi" (ST41) groups than in the "Dubi" (ST35) group (P < 0.01), suggesting different effects of EA stimulation of different acupoints in the same one meridian. No significant differences were found among the "Ximen" (PC4), "Quze" (PC3), "Housanli" (ST36) and "Jiexi" (ST 41) groups, and between the "Daling" (PC7) and model groups, and between the non-acupoint and model groups in the rising rates of both HR and MAP (P > 0.05). (2) Regarding the effects of EA of different tissue layers in "Ximen" (PC4) and "Housanli" (ST36) areas, the rising rates of HR were markedly higher in the PC 4-skin group than in the "Ximen" (PC4), PC4-muscle and PC 4-periosteum groups (P < 0.01), and considerably higher in the "Housanli" (ST36), ST 36-skin, and ST 36-muscle groups than in ST 36-periosteum group (P < 0.05). The rising rates of MAP were significantly higher in the PC 4-skin and PC 4-muscle groups than in the "Ximen" (PC4) and PC4-periosteum groups (P < 0.01), and considerably higher in the ST36-skin group than in the "Housanli" (ST36), ST36-muscle and ST36-periosteum groups (P < 0.01), suggesting different effects of EA stimulation of different tissue layers in the same one acupoint. No significant differences were found between the "Ximen" (PC 4) and PC 4-muscle groups, among the "Housanli" (ST36), ST36-skin and ST 36-muscle groups in the rising rates of HR, between the "Ximen" (PC 4) and PC4-periosteum groups, and among the "Housanli" (ST36), ST 36-muscle and ST36-periosteum groups in the rising rates of MAP (P > 0.05). (3) The effect of the PC 4-skin group was significantly superior to that of the ST 36-skin group in increasing HR (P < 0.01), and the effect of the PC 4-muscle group was obviously stronger than that of the ST 36-muscle group in raising MAP (P < 0.01), suggesting different therapeutic effects of EA stimulation of the similar tissue in different meridian-acupoints. The effects of the "Ximen"(PC4) and "Housanli" (ST36) groups in raising both HR and MAP, and that of the PC 4-muscle and ST 36-muscle groups in upregulating HR, and that of the PC 4-periosteum and ST 36-periosteum groups in raising MAP were comparable (P > 0.05).
Conclusion: EA of different acupoints of the same one meridian, the similar structure of different meridian acupoints and different tissue layers of the same one acupoint have their own relatively specific effects in upregulating HR and MAP in hypotension plus bradycardia rats.