Doyle W J, Seroky J T
Department of Otolaryngology, Children's Hospital of Pittsburgh, Pennsylvania.
Ann Otol Rhinol Laryngol. 1994 Aug;103(8 Pt 1):636-45. doi: 10.1177/000348949410300811.
The mechanism of gas exchange between the middle ear and tissue is fundamental to understanding middle ear physiology and pathophysiology. In this study, the middle ears of six rhesus monkeys were inflated on separate occasions with nitrogen (N2), carbon dioxide (CO2), and oxygen (O2), and middle ear pressures were recorded at defined times postinflation for up to 4 hours. From these data, rate constants governing the exchange of these gases were estimated and compared to those predicted under both diffusion and perfusion limitations. The results show that the rate constants for middle ear to tissue exchange of O2 and CO2 are consistent with a diffusion-limited process. In contrast, middle ear pressure did not decrease over the study period following introduction of N2 into the middle ear. This is interpretable as a much slower rate of N2 exchange than that predicted by either perfusion or diffusion-limited models calibrated to the O2 and CO2 rate constants. These results have significant implications for middle ear gas exchange and suggest that for relatively short observation periods, the behavior of middle ear pressure is controlled by experimentally established O2 and CO2 gradients.
中耳与组织之间的气体交换机制是理解中耳生理学和病理生理学的基础。在本研究中，六只恒河猴的中耳在不同时间分别用氮气（N₂）、二氧化碳（CO₂）和氧气（O₂）充气，并在充气后特定时间记录中耳压力，最长记录4小时。根据这些数据，估算了控制这些气体交换的速率常数，并与在扩散和灌注限制条件下预测的速率常数进行比较。结果表明，中耳与组织之间O₂和CO₂交换的速率常数与扩散限制过程一致。相比之下，向中耳引入N₂后，在研究期间中耳压力并未降低。这可以解释为N₂交换速率比根据O₂和CO₂速率常数校准的灌注或扩散限制模型预测的速率要慢得多。这些结果对中耳气体交换具有重要意义，并表明在相对较短的观察期内，中耳压力的变化受实验确定的O₂和CO₂梯度控制。
