Spyer K M, Thomas T
Royal Free and University College Medical School, University College London, Rowland Hill Street, NW3 2PF, London, UK.
J Auton Nerv Syst. 2000 Jul 3;81(1-3):228-35. doi: 10.1016/s0165-1838(00)00118-1.
ATP has been shown to act as an excitatory neurotransmitter in the central nervous system. In this review, evidence is presented to indicate that when ATP is micro-injected into the ventrolateral medulla (VLM) of the rat, changes in respiratory activity are elicited. These effects, and accompanying changes in heart rate and blood pressure are mediated by P2X purinoreceptors. Immunocytochemistry indicates a prevalence of P2X(2) and P2X(6) purinoreceptors in this region of the medulla. The P2 purinoceptor antagonists, suramin and PPADS blunt the respiratory responses to changes in arterial CO(2) levels when micro-injected into the VLM. This effect is shown electrophysiologically to be mediated by purinoreceptors located primarily on respiratory neurones of the VLM including the Bötzinger complex. As the effects of agonist activation of P2X(2) purinoceptors expressed in HEK293 cells and Xenopus oocytes are potentiated by lowering pH, these data imply that the central respiratory response to CO(2) depends in part on the pH sensitivity of purinoreceptors located on inspiratory neurones. The implications for respiratory activity and control are discussed.
三磷酸腺苷（ATP）已被证明在中枢神经系统中作为一种兴奋性神经递质发挥作用。在本综述中，有证据表明，当将ATP微量注射到大鼠延髓腹外侧（VLM）时，会引发呼吸活动的变化。这些效应以及伴随的心率和血压变化是由P2X嘌呤受体介导的。免疫细胞化学表明，P2X（2）和P2X（6）嘌呤受体在延髓的该区域普遍存在。当将P2嘌呤受体拮抗剂苏拉明和吡哆醛-6-偶氮-2'-磺酸（PPADS）微量注射到VLM中时，它们会减弱对动脉血二氧化碳（CO₂）水平变化的呼吸反应。从电生理学角度来看，这种效应是由主要位于VLM呼吸神经元（包括包钦格复合体）上的嘌呤受体介导的。由于在人胚肾293（HEK293）细胞和非洲爪蟾卵母细胞中表达的P2X（2）嘌呤受体激动剂激活的效应会因降低pH值而增强，这些数据表明，中枢对CO₂的呼吸反应部分取决于位于吸气神经元上的嘌呤受体的pH敏感性。本文还讨论了这些发现对呼吸活动和控制的意义。
