Qin Lu, Li Qin, Li Jianhua
Heart and Vascular Institute The Pennsylvania State University College of Medicine Hershey Pennsylvania USA.
FASEB Bioadv. 2022 Jan 25;4(5):329-341. doi: 10.1096/fba.2021-00156. eCollection 2022 May.
In peripheral artery disease (PAD), the metaboreceptor and mechanoreceptor in muscle afferent nerves contribute to accentuated sympathetic outflow via a neural reflex termed exercise pressor reflex (EPR). Particularly, lactic acid and adenosine triphosphate (ATP) produced in exercising muscles respectively stimulate acid sensing ion channel subtype 3 (ASIC3) and P2X3 receptors (P2X3) in muscle afferent nerves, inducing the reflex sympathetic and BP responses. Previous studies indicated that those two receptors are spatially close to each other and AISC3 may have a regulatory effect on the function of P2X3. This inspired our investigation on the P2X3-mediated EPR response following AISC abolished, which was anticipated to shed light on the future pharmacological and genetic treatment strategy for PAD. Thus, we tested the experimental hypothesis that the pressor response to P2X3 stimulation is greater in PAD rats with 3 days of femoral artery occlusion and the sensitizing effects of P2X3 are attenuated following ASIC knockout (KO) in PAD. Our data demonstrated that in wild type (WT) rats femoral occlusion exaggerated BP response to activation of P2X3 using α,β-methylene ATP injected into the arterial blood supply of the hindlimb, meanwhile the western blot analysis suggested upregulation of P2X3 expression in dorsal root ganglion supplying the afferent nerves. Using the whole cell patch-clamp method, we also showed that P2X3 stimulation enhanced the amplitude of induced currents in muscle afferent neurons of PAD rats. Of note, amplification of the P2X3 evoked-pressor response and expression and current response of P2X3 was attenuated in ASIC3 KO rats. We concluded that the exaggerated P2X3-mediated pressor response in PAD rats is blunted by ASIC KO due to the decreased expression and activities of P2X3 in muscle afferent neurons.
在周围动脉疾病（PAD）中，肌肉传入神经中的代谢感受器和机械感受器通过一种称为运动加压反射（EPR）的神经反射，促使交感神经输出增强。具体而言，运动肌肉中产生的乳酸和三磷酸腺苷（ATP）分别刺激肌肉传入神经中的酸敏感离子通道亚型3（ASIC3）和P2X3受体（P2X3），引发反射性交感神经反应和血压反应。先前的研究表明，这两种受体在空间上彼此靠近，并且ASIC3可能对P2X3的功能具有调节作用。这激发了我们对ASIC被消除后P2X3介导的EPR反应的研究，预计这将为PAD的未来药理和基因治疗策略提供线索。因此，我们检验了实验假设，即在股动脉闭塞3天的PAD大鼠中，对P2X3刺激的加压反应更大，并且在PAD大鼠中ASIC基因敲除（KO）后，P2X3的致敏作用减弱。我们的数据表明，在野生型（WT）大鼠中，股动脉闭塞会夸大后肢动脉血供中注入α,β-亚甲基ATP对P2X3激活的血压反应，同时蛋白质免疫印迹分析表明，供应传入神经的背根神经节中P2X3表达上调。使用全细胞膜片钳方法，我们还表明，P2X3刺激增强了PAD大鼠肌肉传入神经元中诱导电流的幅度。值得注意的是，在ASIC3基因敲除大鼠中，P2X3诱发的加压反应以及P2X3的表达和电流反应的放大作用减弱。我们得出结论，由于肌肉传入神经元中P2X3的表达和活性降低，ASIC基因敲除使PAD大鼠中P2X3介导的加压反应夸大现象减弱。
