Gozal D, Torres J E, Gozal Y M, Nuckton T J
Department of Pediatrics, Tulane University School of Medicine, New Orleans, La 70112, USA.
Biol Neonate. 1996;70(5):280-8. doi: 10.1159/000244377.
With increasing postnatal age, mammals display diminished tolerances for prolonged exposures to severe oxygen deprivation. Similarly, duration and efficiency of gasping, a unique mechanism for enhancing survival after anoxia-induced apnea, are also affected by postnatal age. We hypothesized that maturational patterns of anoxia-induced gasping may encompass more than a single monophasic phenomenon. Each of the putative phases of the gasping response may underlie unique characteristics which could be of relevance to survival capability. To study these issues, adult rats and rat pups at 2-3, 5, 10, 15, and 25 days of age underwent anoxic exposures with 100% N2 in a barometric chamber. In pups aged < 25 days but not thereafter, following an age-dependent period of central apnea, an initial gasping phase characterized by vigorous and frequent periodic bursts of a large inspiratory effort preceded and followed by expiration excursions emerged (phase I). This phase was followed by a period of relative respiratory silence of variable duration with occasional, interspersed phase I-like gasps (phase II). Finally, a third phase easily recognized by the onset of frequent inspiratory-only gasping efforts developed (phase III). The amplitude of phase III inspiratory gasps progressively diminished until their complete cessation. Although overlap between gasping phases was present, a marked age dependency in both duration and gasping frequency within each phase occurred. We conclude that anoxia-induced gasping responses in rat pups < 25 days old are triphasic in nature, exhibit defined phase-locked periodicities and respiratory effort patterns, and undergo significant maturation.
随着出生后年龄的增加，哺乳动物对长时间暴露于严重缺氧的耐受性降低。同样，喘息作为缺氧诱导的呼吸暂停后提高生存率的一种独特机制，其持续时间和效率也受出生后年龄的影响。我们假设缺氧诱导的喘息成熟模式可能不仅仅是单一的单相现象。喘息反应的每个假定阶段可能具有与生存能力相关的独特特征。为了研究这些问题，成年大鼠以及2至3日龄、5日龄、10日龄、15日龄和25日龄的幼鼠在气压舱中接受100%氮气的缺氧暴露。在25日龄以下但此后不再如此的幼鼠中，在经历一段与年龄相关的中枢性呼吸暂停期后，出现了一个初始喘息阶段（I期），其特征是在吸气努力之前和之后有呼气动作，有强烈且频繁的周期性大吸气努力爆发。此阶段之后是一段持续时间可变的相对呼吸静止期，其间偶尔穿插有类似I期的喘息（II期）。最后，出现了第三个阶段（III期），其特征是开始频繁出现仅吸气的喘息努力。III期吸气喘息的幅度逐渐减小直至完全停止。尽管喘息阶段之间存在重叠，但每个阶段的持续时间和喘息频率均存在明显的年龄依赖性。我们得出结论，25日龄以下幼鼠的缺氧诱导喘息反应本质上是三相的，表现出明确的锁相周期性和呼吸努力模式，并且经历了显著的成熟过程。
