Department of Physiology, Basic Medical College of Nanchang University, Bayi Road 461, Nanchang 330006, PR China.
Neurochem Int. 2010 Jul;56(8):984-90. doi: 10.1016/j.neuint.2010.04.010. Epub 2010 Apr 18.
The restructuring of cardiac innervation after myocardial ischemic injury, which is often associated with an increased sympathoexcitatory reflex characterized by an increase in blood pressure and sympathetic nerve activity. This study observed whether P2X(2/3) receptor in rat superior cervical ganglion (SCG) played a role in the increased sympathoexcitatory reflex induced by myocardial ischemic nociceptive signaling. The findings showed that the systolic blood pressure, heart rate and respiration in the myocardial ischemic rats were higher than those in control rats. The content of adenosine 5'-triphosphate (ATP) from myocardial ischemic group was higher than that from control group. After myocardial ischemic rats were treated with selective P2X(2/3) receptor antagonist A-317491, the content of ATP in SCG was reduced. Coexpression value of P2X(2), P2X(3) and tyrosine hydroxylase (TH) in the SCG and myocardial tissues of myocardial ischemic group was increased significantly, compared with that in the SCG and myocardial tissues of control group. The expression value of P2X(2), P2X(3) and TH in the SCG and myocardial tissues of myocardial ischemic rats treated with A-317491 was decreased. The amplitude of the currents was much larger in myocardial ischemic group than that obtained in control group after administration of ATP with the same concentration. After the myocardial ischemic rats were treated with A-317491, ATP-activated currents were reduced. The myocardial ischemic injury induced an increase in the expression of P2X(2/3) receptor colocalization with TH and a hypersensitivity state of SCG neurons to ATP, which led to the increased sympathoexcitatory reflex.
心肌缺血损伤后心脏神经支配的重构,常伴有血压和交感神经活性增加的交感兴奋反射增强。本研究观察了大鼠颈上交感神经节(SCG)中 P2X(2/3)受体是否在心肌缺血伤害性信号诱导的交感兴奋反射增强中起作用。结果显示,心肌缺血大鼠的收缩压、心率和呼吸频率均高于对照组;心肌缺血组的三磷酸腺苷(ATP)含量高于对照组;给予选择性 P2X(2/3)受体拮抗剂 A-317491 后,心肌缺血大鼠的 SCG 中 ATP 含量降低;与对照组的 SCG 和心肌组织相比,心肌缺血组的 SCG 和心肌组织中 P2X(2)、P2X(3)和酪氨酸羟化酶(TH)的共表达值明显增加;给予 A-317491 后,心肌缺血大鼠的 SCG 和心肌组织中 P2X(2)、P2X(3)和 TH 的表达值降低;与对照组相比,给予相同浓度的 ATP 后,心肌缺血组的电流幅度明显更大;给予 A-317491 后,ATP 激活的电流减少。心肌缺血损伤引起 P2X(2/3)受体与 TH 共表达增加,以及 SCG 神经元对 ATP 的超敏状态,导致交感兴奋反射增强。