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Objective Myocardial ischemia activates cardiac sympathetic afferent nerve endings and elicits chest pain, which is often associated with a sympathoexcitatory reflex characterized by an increase in blood pressure and sympathetic nerve activity.P2X7 channel is responsible for the release of cardioprotectants induced by ischemic pre-and postconditioning.Puerarin (a major active ingredient extracted from the traditional Chinese medicine Ge-gen) is widely used in the treatment of cardiovascular disease in China.The present study was aimed to observe the effect of puerarin on sympathoexcitatory reflex induced by myocardial ischemic nociceptive signaling via P2X7 receptor in rat superior cervical ganglion (SCG).Methods Myocardial ischemia model was established.Sprague-Dawley rat were randomly divided into group Ⅰ (Sham group), group Ⅱ (Puerarin, intraperitoneal injection), group Ⅲ (Myocardial ischemia injury), group Ⅳ (Myocardial ischemia injury + Puerarin) and group Ⅴ (Blank control).Electrocardiogram (ECG) of the rats were measured.Systolic blood pressure, heart rate and respiration were measured by non-invasive blood pressure determinator with different transducer.The expression of P2X7 mRNA and protein was analyzed by PCR, Western blotting and immunohistochemistry.Results The results showed that the systolic blood pressure, heart rate and respiration in group Ⅲ were higher than those in group Ⅰ, Ⅲ, Ⅴ (P<0.01).There was no difference in group Ⅰ, Ⅱ and Ⅴ (P>0.05).After the treatment with puerarin in the myocardial ischemie rats, systolic blood pressure, heart rate and respiration in group Ⅳ were lower than those in group Ⅲ (P<0.05).The expression of P2X7 protein and mRNA in SCG of myocardial ischemic injury rats were increased compared with those in control rats.Puerarin decreased the P2X7 protein and mRNA expression in SCG of myocardial ischemic injury rats.Conclusions According to these results, we conclude that puerarin can reduce the transmission of myocardial ischemic signalling mediated by P2X7 receptor in rat sympathetic ganglion neurons.