The involvement of P2X3 receptors of rat sympathetic ganglia in cardiac nociceptive transmission

In this work we have examined the effects of P2X(3) receptor antagonist A-317491 on P2X(3) expression in superior cervical ganglion (SCG) from naive and myocardial ischemic rats to observe the effect of P2X(3) receptors in cardiac nociceptive transmission. A-317491 improved nociceptive behavior. In the ganglia neurons of rats at 14 days after myocardial ischemic injury, the staining of P2X(3) receptor in myocardial ischemic groups appeared to be more intense than those of naive rats detected by immunohistochemistry. After myocardial ischemic rats treated with A-317491, the intensity of the P2X(3) immunoreactivity was lower than that in myocardial ischemic rats. The signals of P2X(3) and its protein and mRNA in myocardial ischemic groups were higher than those in control group measured by western blotting and in situ hybridization. After myocardial ischemic rats treated with A-317491, the intensity of the P2X(3) and its mRNA was lower than that in myocardial ischemic rats. These results suggest the involvement of P2X(3) receptors in cardiac nociceptive transmission and A-317491 may inhibit the transmission mediated by P2X(3) receptors in rat SCG after myocardial ischemia.