Doyle W J, Alper C M, Seroky J T, Karnavas W J
Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh and the University of Pittsburgh School of Medicine, PA, USA.
Acta Otolaryngol. 1998 Jul;118(4):567-73. doi: 10.1080/00016489850154748.
The exchange rates of CO2 and He across the tympanic membrane were estimated in 5 monkeys. For these experiments, the monkey was anesthetized and one arm of a polyethylene "T" tube was introduced into the external canal of the test ear and sealed to the ambient environment with wax. One arm of the T tube was attached to a pressure transducer and the other to an argon gas source via a valve. Silica tubing sealed within the probe provided periodic gas samples for composition analysis by an online mass spectrometer. Prior to each experiment, the probe was washed with Argon. In 5 experiments the probe was sealed within the external canal of animals with physiological middle ear gas compositions, and in 5 experiments the probe was sealed within the external canal of animals whose middle ears were partially washed with He. The gas in the probe was sampled and analyzed at 10-min intervals for up to 4 h. The results documented a significant increase in the percentage composition of CO2 but not He in the experiments conducted with physiological middle ear gas compositions, and increases in both He and CO2 in the experiments conducted after the middle ear was washed with He. Estimated, average exchange constants for He and CO2 were 0.0005 microl/min/mmHg and 0.0103 microl/min/mmHg, respectively. Using data from previous experiments, the relative trans-mucosal to trans-tympanic membrane gas exchange rates in monkeys are estimated to be in the order of 10:1 for inert gases and 180:1 for chemically active gases.
在5只猴子身上估算了二氧化碳（CO2）和氦气（He）穿过鼓膜的速率。在这些实验中，将猴子麻醉，把一根聚乙烯“T”形管的一个臂插入受试耳的外耳道，并用蜡密封使其与周围环境隔绝。“T”形管的一个臂连接到压力传感器，另一个臂通过阀门连接到氩气源。密封在探头内的硅胶管提供定期气体样本，以便通过在线质谱仪进行成分分析。每次实验前，探头用氩气冲洗。在5次实验中，探头密封在具有生理性中耳气体成分的动物外耳道内；在另外5次实验中，探头密封在中耳部分用氦气冲洗过的动物外耳道内。每隔10分钟对探头内的气体进行采样和分析，持续4小时。结果表明，在具有生理性中耳气体成分的实验中，二氧化碳的百分比组成显著增加，而氦气没有；在用氦气冲洗中耳后的实验中，氦气和二氧化碳的含量均增加。估算得出，氦气和二氧化碳的平均交换常数分别为0.0005微升/分钟/毫米汞柱和0.0103微升/分钟/毫米汞柱。根据之前实验的数据，估计猴子中惰性气体的跨黏膜与跨鼓膜气体交换速率之比约为10:1，化学活性气体的该比值约为180:1。
