Development of ventilatory chemoreflexes in Coturnix quail chicks

Publication date: Available online 14 February 2020Source: Respiratory Physiology & NeurobiologyAuthor(s): Monata J. Song, Ashley E. Pratt, Ryan W. BavisAbstractCompared 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 develo...
Source: Respiratory Physiology and Neurobiology - Category: Respiratory Medicine Source Type: research