New Jersey Institute of Technology and Rutgers University, 195 University Drive, Boyden Hall, Newark, NJ 07102, USA.
J Neurophysiol. 2011 Feb;105(2):625-39. doi: 10.1152/jn.00237.2010. Epub 2010 Nov 17.
Neurons depend on aerobic metabolism, yet are very sensitive to oxidative stress and, as a consequence, typically operate in a low O(2) environment. The balance between blood flow and metabolic activity, both of which can vary spatially and dynamically, suggests that local O(2) availability markedly influences network output. Yet the understanding of the underlying O(2)-sensing mechanisms is limited. Are network responses regulated by discrete O(2)-sensing mechanisms or, rather, are they the consequence of inherent O(2) sensitivities of mechanisms that generate the network activity? We hypothesized that a broad range of O(2) tensions progressively modulates network activity of the pre-Bötzinger complex (preBötC), a neuronal network critical to the central control of breathing. Rhythmogenesis was measured from the preBötC in transverse neonatal mouse brain stem slices that were exposed to graded reductions in O(2) between 0 and 95% O(2), producing tissue oxygenation values ranging from 20 ± 18 (mean ± SE) to 440 ± 56 Torr at the slice surface, respectively. The response of the preBötC to graded changes in O(2) is progressive for some metrics and abrupt for others, suggesting that different aspects of the respiratory network have different sensitivities to O(2).
神经元依赖有氧代谢，但对氧化应激非常敏感，因此通常在低氧环境中运作。血液流量和代谢活动之间的平衡，两者都可以在空间和动态上发生变化，这表明局部氧气供应显著影响网络输出。然而，对潜在的氧感应机制的理解是有限的。网络响应是否受离散的氧感应机制调节，或者它们是否是产生网络活动的机制固有氧敏感性的结果？我们假设，广泛的氧张力逐渐调节了预脑桥复合体（preBötC）的网络活动，该网络对于呼吸的中枢控制至关重要。在暴露于 0 到 95%氧之间的分级氧减少的情况下，从脑桥切片的预脑桥测量节律发生，分别在切片表面产生从 20 ± 18（平均值 ± SE）到 440 ± 56 托的组织氧合值。预脑桥对氧分压的分级变化的反应在某些指标上是渐进的，而在其他指标上是突然的，这表明呼吸网络的不同方面对氧有不同的敏感性。
