Abstract
Acupuncture has been used to alleviate cardiac dysfunction (e.g., tachycardia). There have been several reports that acupuncture produces a decrease in heart rate in healthy human subjects. However, the neural mechanism of this response is still controversial. I would like to introduce our recent study on the neural mechanism of acupuncture on heart rate in anesthetized rats. Acupuncture stimulation of various areas (forepaw, forelimb, chest, abdomen, hindlimb, hindpaw) produced decrease in heart rate. The acupuncture-induced decrease in heart rate was abolished by severance of the somatic nerves ipsilateral to the site of stimulation. Heart rate was decreased by acupuncture stimulation of the muscle alone, but not of the skin alone. The acupuncture-induced decrease in heart rate was not significantly influenced by severance of both vagus nerves at the cervical level but was abolished by bilateral stellectomy. Acupuncture stimulation decreased cardiac sympathetic efferent nerve activity as well as heart rate. After spinal transection at the C1 level, the bradycardiac responses to stimulation of hindpaw and hidlimb were abolished, while those of the forepaw, forelimb, chest and abdomen reversed to tachycardiac responses. These results suggest that the decrease in heart rate produced by acupuncture stimulation is a reflex response. The afferent pathway is composed of muscle afferents while the efferent pathway is composed of cardiac sympathetic nerves. The reflex center is located in the brain. The spinally-mediated reflex increases in heart rate seem to be inhibited by inhibitory descending pathways originating in the brain. [J Physiol Sci. 2008;58 Suppl:S8]
