Putnam Robert W, Conrad Susan C, Gdovin M J, Erlichman Joseph S, Leiter J C
Department of Anatomy and Physiology, Wright State University School of Medicine, 3640 Colonel Glenn Highway, Dayton, OH 45435, USA.
Respir Physiol Neurobiol. 2005 Nov 15;149(1-3):165-79. doi: 10.1016/j.resp.2005.03.004.
The ventilatory response to CO2 changes as a function of neonatal development. In rats, a ventilatory response to CO2 is present in the first 5 days of life, but this ventilatory response to CO2 wanes and reaches its lowest point around postnatal day 8. Subsequently, the ventilatory response to CO2 rises towards adult levels. Similar patterns in the ventilatory response to CO2 are seen in some other species, although some animals do not exhibit all of these phases. Different developmental patterns of the ventilatory response to CO2 may be related to the state of development of the animal at birth. The triphasic pattern of responsiveness (early decline, a nadir, and subsequent achievement of adult levels of responsiveness) may arise from the development of several processes, including central neural mechanisms, gas exchange, the neuromuscular junction, respiratory muscles and respiratory mechanics. We only discuss central neural mechanisms here, including altered CO2 sensitivity of neurons among the various sites of central CO2 chemosensitivity, changes in astrocytic function during development, the maturation of electrical and chemical synaptic mechanisms (both inhibitory and excitatory mechanisms) or changes in the integration of chemosensory information originating from peripheral and multiple central CO2 chemosensory sites. Among these central processes, the maturation of synaptic mechanisms seems most important and the relative maturation of synaptic processes may also determine how plastic the response to CO2 is at any particular age.
对二氧化碳的通气反应随新生儿发育而变化。在大鼠中，出生后前5天存在对二氧化碳的通气反应，但这种对二氧化碳的通气反应会减弱，并在出生后第8天左右达到最低点。随后，对二氧化碳的通气反应向成年水平上升。在其他一些物种中也观察到对二氧化碳通气反应的类似模式，尽管有些动物并不表现出所有这些阶段。对二氧化碳通气反应的不同发育模式可能与动物出生时的发育状态有关。反应性的三相模式（早期下降、最低点以及随后达到成年水平的反应性）可能源于几个过程的发展，包括中枢神经机制、气体交换、神经肌肉接头、呼吸肌和呼吸力学。我们在此仅讨论中枢神经机制，包括中枢二氧化碳化学感受器各个部位神经元对二氧化碳敏感性的改变、发育过程中星形胶质细胞功能的变化、电突触和化学突触机制（抑制性和兴奋性机制）的成熟，或源自外周和多个中枢二氧化碳化学感受器部位的化学感觉信息整合的变化。在这些中枢过程中，突触机制的成熟似乎最为重要，突触过程的相对成熟也可能决定在任何特定年龄对二氧化碳的反应有多可塑。
