Regulation of breathing and autonomic outflows by chemoreceptors.
Regulation of breathing and autonomic outflows by chemoreceptors.
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DOI：
10.1002/cphy.c140004
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发表时间：
2014-10
影响因子：
5.8
通讯作者：
Guyenet PG
中科院分区：
文献类型：
--
作者：
Guyenet PG
肺通气量随行为而大幅波动，但动脉 PCO2 保持稳定。在正常情况下，化学反射通过产生由下脑干回路介导的小幅校正性心肺调节来促进 PaCO2 稳定性。颈动脉体 (CB) 信息通过孤核 (NTS) 谷氨酸能神经元到达呼吸模式发生器 (RPG)，该神经元还针对头侧延髓腹外侧 (RVLM) 前交感神经元，从而提高交感神经活动 (SNA)。化学感受器还通过 RPG 的输入间接调节交感前神经元和心迷走神经节前神经元。化学感受器对自主神经流出的次要影响是由肺牵张传入和压力感受器活动的变化引起的。中枢呼吸系统化疗敏感性是由酸对神经元的直接作用和二氧化碳通过星形胶质细胞的间接作用引起的。中枢呼吸化学感受器尚未明确确定，但梯形后核（RTN）是一个特别有力的候选者。 RTN 的缺乏可能会导致先天性中枢性低通气综合征的严重中枢性呼吸暂停。与其他压力源一样，强烈的化学感应刺激会产生唤醒并激活促进唤醒或注意力的回路。这些通路（例如，蓝斑、中缝和食欲素系统）以状态依赖性方式调节化学反射，并且它们被强烈的化学感应刺激激活会增强这些反射。在原发性高血压、阻塞性睡眠呼吸暂停和充血性心力衰竭中，长期升高的 CB 传入活动有助于提高 SNA，但呼吸没有变化或变得周期性（严重 CHF）。中枢神经系统极度缺氧会产生刻板的心肺反应（喘气、SNA 增加）。讨论了这些不同的病理对脑干心肺网络的影响，特别考虑了中枢和外周化学反射之间的相互作用。
Lung ventilation fluctuates widely with behavior but arterial PCO2 remains stable. Under normal conditions, the chemoreflexes contribute to PaCO2 stability by producing small corrective cardiorespiratory adjustments mediated by lower brainstem circuits. Carotid body (CB) information reaches the respiratory pattern generator (RPG) via nucleus solitarius (NTS) glutamatergic neurons which also target rostral ventrolateral medulla (RVLM) presympathetic neurons thereby raising sympathetic nerve activity (SNA). Chemoreceptors also regulate presympathetic neurons and cardiovagal preganglionic neurons indirectly via inputs from the RPG. Secondary effects of chemoreceptors on the autonomic outflows result from changes in lung stretch afferent and baroreceptor activity. Central respiratory chemosensitivity is caused by direct effects of acid on neurons and indirect effects of CO2 via astrocytes. Central respiratory chemoreceptors are not definitively identified but the retrotrapezoid nucleus (RTN) is a particularly strong candidate. The absence of RTN likely causes severe central apneas in congenital central hypoventilation syndrome. Like other stressors, intense chemosensory stimuli produce arousal and activate circuits that are wake- or attention-promoting. Such pathways (e.g., locus coeruleus, raphe, and orexin system) modulate the chemoreflexes in a state-dependent manner and their activation by strong chemosensory stimuli intensifies these reflexes. In essential hypertension, obstructive sleep apnea and congestive heart failure, chronically elevated CB afferent activity contributes to raising SNA but breathing is unchanged or becomes periodic (severe CHF). Extreme CNS hypoxia produces a stereotyped cardiorespiratory response (gasping, increased SNA). The effects of these various pathologies on brainstem cardiorespiratory networks are discussed, special consideration being given to the interactions between central and peripheral chemoreflexes.