Department of Physiology, Centre for Neuroscience, Women & Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
Compr Physiol. 2013 Jan;3(1):331-63. doi: 10.1002/cphy.c120004.
The main functions of the respiratory neural network are to produce a coordinated, efficient, rhythmic motor behavior and maintain homeostatic control over blood oxygen and CO2/pH levels. Purinergic (ATP) signaling features prominently in these homeostatic reflexes. The signaling actions of ATP are produced through its binding to a diversity of ionotropic P2X and metabotropic P2Y receptors. However, its net effect on neuronal and network excitability is determined by the interaction between the three limbs of a complex system comprising the signaling actions of ATP at P2Rs, the distribution of multiple ectonucleotidases that differentially metabolize ATP into ADP, AMP, and adenosine (ADO), and the signaling actions of ATP metabolites, especially ADP at P2YRs and ADO at P1Rs. Understanding the significance of purinergic signaling is further complicated by the fact that neurons, glia, and the vasculature differentially express P2 and P1Rs, and that both neurons and glia release ATP. This article reviews at cellular, synaptic, and network levels, current understanding and emerging concepts about the diverse roles played by this three-part signaling system in: mediating the chemosensitivity of respiratory networks to hypoxia and CO2/pH; modulating the activity of rhythm generating networks and inspiratory motoneurons, and; controlling blood flow through the cerebral vasculature.
呼吸神经网络的主要功能是产生协调、高效、有节奏的运动行为，并维持血液氧和二氧化碳/酸碱度水平的体内平衡控制。嘌呤能（ATP）信号在这些体内平衡反射中起着重要作用。ATP 的信号作用是通过其与多种离子型 P2X 和代谢型 P2Y 受体结合产生的。然而，其对神经元和网络兴奋性的净效应取决于一个复杂系统的三个分支之间的相互作用，该系统包括 P2R 上的 ATP 信号作用、多种核苷酸酶的分布，这些核苷酸酶将 ATP 不同地代谢为 ADP、AMP 和腺苷（ADO），以及 ATP 代谢物的信号作用，特别是 P2YR 上的 ADP 和 P1R 上的 ADO。嘌呤能信号的重要性进一步复杂化，因为神经元、神经胶质和血管以不同的方式表达 P2 和 P1R，并且神经元和神经胶质都释放 ATP。本文在细胞、突触和网络水平上，综述了这一三分信号系统在以下方面的不同作用的最新认识和新出现的概念：介导呼吸网络对缺氧和二氧化碳/酸碱度的化学敏感性；调节节律产生网络和吸气运动神经元的活性；以及控制脑血管的血流量。
