Deitmer J W, Rose C R
Abteilung für Allgemeine Zoologie, Universität Kaiserslautern, Germany.
Prog Neurobiol. 1996 Feb;48(2):73-103. doi: 10.1016/0301-0082(95)00039-9.
The regulation of H+ in nervous systems is a function of several processes, including H+ buffering, intracellular H+ sequestering, CO2 diffusion, carbonic anhydrase activity and membrane transport of acid/base equivalents across the cell membrane. Glial cells participate in all these processes and therefore play a prominent role in shaping acid/base shifts in nervous systems. Apart from a homeostatic function of H(+)-regulating mechanisms, pH transients occur in all three compartments of nervous tissue, neurones, glial cells and extracellular spaces (ECS), in response to neuronal stimulation, to neurotransmitters and hormones as well as secondary to metabolic activity and ionic membrane transport. A pivotal role for H+ regulation and shaping these pH transients must be assigned to the electrogenic and reversible Na(+)-HCO3-membrane cotransport, which appears to be unique to glial cells in nervous systems. Activation of this cotransporter results in the release and uptake of base equivalents by glial cells, processes which are dependent on the glial membrane potential. Na+/H+ and Cl-/HCO3-exchange, and possibly other membrane carriers, accomplish the set of tools in both glial cells and neurones to regulate their intracellular pH. Due to the pH dependence of a great variety of processes, including ion channel gating and conductances, synaptic transmission, intercellular communication via gap junctions, metabolite exchange and neuronal excitability, rapid and local pH transients may have signalling character for the information processing in nervous tissue. The impact of H+ signalling under both physiological and pathophysiological conditions will be discussed for a variety of nervous system functions.
神经系统中H⁺的调节是多个过程的功能，包括H⁺缓冲、细胞内H⁺隔离、CO₂扩散、碳酸酐酶活性以及酸碱等价物跨细胞膜的膜转运。神经胶质细胞参与所有这些过程，因此在塑造神经系统中的酸碱变化方面发挥着重要作用。除了H⁺调节机制的稳态功能外，在神经组织的所有三个部分，即神经元、神经胶质细胞和细胞外空间（ECS）中，都会因神经元刺激、神经递质和激素以及继发于代谢活动和离子膜转运而出现pH瞬变。H⁺调节和塑造这些pH瞬变的关键作用必须归因于电生的和可逆的Na⁺-HCO₃膜共转运体，这似乎是神经系统中神经胶质细胞所特有的。该共转运体的激活导致神经胶质细胞释放和摄取碱基等价物，这些过程依赖于神经胶质细胞膜电位。Na⁺/H⁺和Cl⁻/HCO₃交换以及可能的其他膜载体，共同构成了神经胶质细胞和神经元调节其细胞内pH的工具集。由于包括离子通道门控和电导、突触传递、通过缝隙连接的细胞间通讯、代谢物交换和神经元兴奋性在内的多种过程都依赖于pH，快速和局部的pH瞬变可能对神经组织中的信息处理具有信号传导作用。将针对多种神经系统功能讨论生理和病理生理条件下H⁺信号传导的影响。
