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Electroacupuncture-induced pressor and chronotropic effects in anesthetized rats
Jiuan-Miaw Liao1, Hua Ting, Shin-Da Lee
1Department of Physiology, College of Medicine Chung-Shan Medical University, No. 110, Chang-Kuo North Rd Section 1, Taichung, Taiwan 10018.
Autonomic Neuroscience : Basic & Clinical
|February 7, 2006
Summary
Electroacupuncture (Ea) at the Hoku acupoint, but not Tsusanli, affects circulatory dynamics in rats. Low-frequency Ea causes a tonic pressor effect, while high-frequency Ea has a phasic effect, both mediated by adrenergic pathways.
Area of Science:
- Physiology
- Neuroscience
- Acupuncture Research
Background:
- Electroacupuncture (Ea) is a therapeutic technique involving electrical stimulation of acupuncture points.
- Understanding the physiological effects of Ea on circulatory dynamics is crucial for its clinical application.
- Previous research has explored Ea's impact on various bodily functions, but specific effects on blood pressure and heart rate require further elucidation.
Purpose of the Study:
- To investigate the effects of low-frequency (LFEa) and high-frequency (HFEa) electroacupuncture on arterial blood pressure (BP) and heart rate (HR) in anesthetized rats.
- To determine the specific acupoints (Tsusanli - St-36, Hoku - Li-4) involved in these circulatory responses.
- To elucidate the underlying neuroadrenergic mechanisms mediating the observed effects.
Main Methods:
- Anesthetized rats were subjected to Ea stimulation at the Tsusanli (St-36) and Hoku (Li-4) acupoints.
- Stimulations were performed using low frequency (2 Hz; LFEa) and high frequency (20 Hz; HFEa) at 20 times motor threshold intensity.
- Arterial blood pressure and heart rate were continuously monitored. Pharmacological interventions included alpha-adrenergic blockade (moxisylyte) and combined alpha- and beta-adrenergic blockade (propranolol).
Main Results:
- Ea stimulation at the Tsusanli point did not affect HR or BP.
- Ea stimulation at the Hoku point elicited significant chronotropic and pressor effects.
- LFEa induced a tonic pressor response, while HFEa produced a phasic pressor response. Alpha-adrenergic blockade attenuated HFEa effects and completely blocked LFEa effects. Combined alpha- and beta-blockade abolished HFEa effects.
Conclusions:
- Electroacupuncture at the Hoku acupoint, with specific frequency parameters, can effectively modulate and maintain blood pressure.
- LFEa primarily activates sympathetic vasomotor tone, leading to a sustained increase in BP.
- HFEa not only activates vasomotor tone but also potentiates sympathetic drive to the heart, resulting in both increased BP and heart rate.
