Puerarin alleviates aggravated sympathoexcitatory response induced by myocardial ischemia via regulating P2X3 receptor in rat superior cervical ganglia

• Puerarin decreased up-expression of P2X3 receptor in SCG after MI.
• Puerarin lowered cardiac injury after down-P2X3 mRNA and protein.
• Puerarin inhibited ATP currents in SCG and HEK293 cells with P2X3.
• Puerarin alleviated up-sympathoexcitatory response via inhibiting P2X3.
• Puerarin blocks P2X3 signaling to protect myocardium.

Myocardial ischemia elicits a sympathoexcitatory response characterized by increase in blood pressure and sympathetic nerve activity. Puerarin, a major active ingredient extracted from the traditional Chinese plant medicine Ge-gen, has been widely used in treatment of myocardial and cerebral ischemia. However, little is known about the mechanism. Our study was aimed to explore the effect of puerarin on sympathoexcitatory response induced by myocardial ischemic injury and possible relationship with P2X3 receptor. Our results showed that puerarin alleviated systolic blood pressure and heart rate, and decreased the up-regulated of P2X3 mRNA and protein in SCG of myocardial ischemic rats. The amplitude of ATP-activated currents of SCG neurons was much larger in myocardial ischemic group than that in control group. Puerarin reduced ATP-activated currents in myocardial ischemic group and control group, and the inhibiting effects of puerarin in myocardial ischemic group were stronger than those in control group. Puerarin also significantly inhibited ATP-activated currents in HEK293 cells transfected with P2X3 receptor. These results suggest that puerarin can depress up-sympathoexcitatory response induced by myocardial ischemia via acting on P2X3 receptor in rat SCG to protect myocardium.