Compared to mammals, little is known about the development of the respiratory control system in birds. In the present study, ventilation and metabolism were measured in Coturnix quail chicks exposed to room air, hypoxia (11 % O2), and hypercapnia (4% CO2) at 0-1, 3-4, and 6-7 days posthatching (dph). Mass-specific ventilation and metabolic rate tended to increase between 0-1 and 3-4 dph and then decrease again between 3-4 and 6-7 dph. The magnitude of the hypoxic ventilatory response (HVR) increased with age. The HVR also exhibited a biphasic shape in younger quail: after the initial increase in ventilation, ventilation declined back to (0-1 dph), or toward (4 dph), baseline. Older chicks (6-7 dph) had a "sustained HVR" in which ventilation remained high throughout the hypoxic challenge. The biphasic HVR did not appear to be caused by a decline in metabolic rate; although hypoxic hypometabolism was observed in quail chicks in all three age groups, the metabolic response appeared to occur more slowly than the biphasic HVR. The biphasic ventilatory response was also specific to hypoxia since the hypercapnic ventilatory response (HCVR) was characterized by a sustained increase in ventilation in all three age groups. The magnitude of the HCVR decreased with age. These results point to several similarities in the development of ventilatory chemorflexes between Coturnix quail and newborn mammals, including age-dependent (1) increases in the HVR, (2) transitions from a biphasic to a sustained HVR, and (3) decreases in the HCVR. Whether homologous mechanisms underlie these developmental changes remains to be determined.

中文翻译：

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Coturnix 鹌鹑雏鸡通气化学反射的发育。

与哺乳动物相比，人们对鸟类呼吸控制系统的发展知之甚少。在本研究中，在孵化后 0-1、3-4 和 6-7 天（dph ）。特定质量的通气和代谢率在 0-1 和 3-4 dph 之间趋于增加，然后在 3-4 和 6-7 dph 之间再次下降。缺氧通气反应 (HVR) 的幅度随着年龄的增长而增加。HVR 在年轻鹌鹑中也表现出双相形状：在最初增加通风后，通风下降回 (0-1 dph) 或接近 (4 dph) 基线。年长的雏鸡 (6-7 dph) 具有“持续的 HVR”，其中在整个缺氧挑战期间通风保持高水平。双相 HVR 似乎不是由代谢率下降引起的；尽管在所有三个年龄组的鹌鹑雏鸡中都观察到缺氧代谢减退，但代谢反应似乎比双相 HVR 发生得更慢。双相通气反应也对缺氧具有特异性，因为高碳酸血症通气反应 (HCVR) 的特点是所有三个年龄组的通气量均持续增加。HCVR 的大小随着年龄的增长而降低。这些结果表明 Coturnix 鹌鹑和新生哺乳动物之间的通气化学反射发展有几个相似之处，包括年龄依赖性 (1) HVR 增加，(2) 从双相转变为持续 HVR，以及 (3) 减少HCVR。同源机制是否是这些发育变化的基础仍有待确定。