Moss T J, Jakubowska A E, McCrabb G J, Billings K, Harding R
Department of Physiology, Monash University, Clayton, Vic., Australia.
Respir Physiol. 1995 Apr;100(1):33-44. doi: 10.1016/0034-5687(94)00113-e.
We aimed to determine the time course of postnatal development of ventilatory responsiveness to progressive hypoxia and hypercapnia. Eight lambs underwent hypoxic and hypercapnic rebreathing tests at weekly intervals from soon after birth to 6 weeks of age. Six mature ewes were also studied. During the tests blood samples were collected at intervals from the aorta so that arterial PO2 (PaO2) and PCO2 (PaCO2) could be related to ventilation. Hypoxic sensitivity was defined as the percentage increase in minute ventilation when PaO2 fell from control values (104.7 +/- 6.9 mmHg) to 50 mmHg. When measured in this way, hypoxic sensitivity increased significantly from 64.2 +/- 19.3% (mean +/- SE) in the newborn (2.3 +/- 0.4 days) to 150.4 +/- 14.0% at 3-4 weeks (25.1 +/- 0.6 days, P = 0.05). The hypoxic sensitivity of ewes (66.3 +/- 16.8%) was greatly reduced compared to 6-week-old lambs (140.3 +/- 18.9%, P < 0.05). Hypercapnic sensitivity (ml.min-1.kg-1.mmHg CO2(-1)) did not change significantly with age. We conclude that hypoxic sensitivity increases during the first 3-4 postnatal weeks and declines between infancy and adulthood. In contrast hypercapnic sensitivity does not change with age, although tidal volume and breathing frequency contributions to ventilatory responses change with advancing postnatal age.
我们旨在确定出生后对渐进性缺氧和高碳酸血症的通气反应性的发育时间进程。八只羔羊从出生后不久至6周龄，每隔一周进行一次缺氧和高碳酸血症重复呼吸试验。还对六只成年母羊进行了研究。在试验期间，每隔一段时间从主动脉采集血样，以便将动脉血氧分压（PaO2）和二氧化碳分压（PaCO2）与通气相关联。缺氧敏感性定义为当PaO2从对照值（104.7±6.9 mmHg）降至50 mmHg时，分钟通气量增加的百分比。以这种方式测量时，缺氧敏感性从新生儿（2.3±0.4天）时的64.2±19.3%（平均值±标准误）显著增加至3 - 4周（25.1±0.6天）时的150.4±14.0%（P = 0.05）。与6周龄羔羊（140.3±18.9%）相比，母羊的缺氧敏感性（66.3±16.8%）大大降低（P < 0.05）。高碳酸血症敏感性（ml·min⁻¹·kg⁻¹·mmHg CO₂⁻¹）并未随年龄显著变化。我们得出结论，缺氧敏感性在出生后的前3 - 4周增加，在婴儿期和成年期之间下降。相比之下，高碳酸血症敏感性不随年龄变化，尽管潮气量和呼吸频率对通气反应的贡献随出生后年龄的增长而变化。
