Malm L, Tjernström O, White P, Ivarsson A
ORL J Otorhinolaryngol Relat Spec. 1987;49(3):138-44. doi: 10.1159/000275924.
The middle ear pressure was increased by air injections and the level (pressure opening level = Pol) at which the Eustachian tube (ET) opened was determined in anaesthetized ras. At a rate of pressure increase of 0.7 kPa/s it opened at 4.1 +/- 0.4 kPa. A change of the body and head position from horizontal to almost vertical increased the Pol by about 0.4 kPa (head downwards) and decreased the Pol by about 0.3 kPa (head upwards). Epinephrine tested in a dose-response experiment had no significant effect on Pol (doses from 0.01 to 10 micrograms/kg body weight). A surface-tension-lowering substance, Tween 20, instilled into the middle ear, reduced Pol by about 1 kPa. A change in body and head position had thus a moderate effect on the passive opening of the ET, a strong decongestant had no effect, and a surface-lowering substance, a marked effect. With increasing rates of pressure change in the middle ear, Pol increased. After instillation of Tween 20 there was an almost parallel shift to lower values of the regression line of the Pol at different rates of pressure increase.
通过注入空气增加中耳压力，并在麻醉的大鼠中确定咽鼓管（ET）开放时的压力水平（压力开放水平=Pol）。以0.7 kPa/s的压力增加速率，它在4.1±0.4 kPa时开放。身体和头部位置从水平变为几乎垂直时，Pol增加约0.4 kPa（头部向下），减少约0.3 kPa（头部向上）。在剂量反应实验中测试的肾上腺素对Pol没有显著影响（剂量为0.01至10微克/千克体重）。注入中耳的降低表面张力的物质吐温20使Pol降低约1 kPa。因此，身体和头部位置的改变对ET的被动开放有中度影响，一种强效减充血剂没有影响，而一种降低表面张力的物质有显著影响。随着中耳压力变化速率的增加，Pol增加。注入吐温20后，在不同压力增加速率下，Pol的回归线几乎平行地向较低值移动。
