Valberg P A, Brain J D
J Appl Physiol Respir Environ Exerc Physiol. 1977 Oct;43(4):730-8. doi: 10.1152/jappl.1977.43.4.730.
Pressure-volume (PV) curves of excised cat, dog, rabbit, and rat lungs were determined in a sequence of three conditions: 1) normal-surface, air-filled; 2) saline-filled; and 3) polyoxyethylene (20) sorbitan monolaurate-(Tween 20) surface, air-filled. Since the surface tension of lung washings containing 2% Tween 20 is constant, the Tween-surface air-filled lungs presumably exhibit the pressure-volume behavior of lungs with constant surface tension. These data along with the assumption of equivalent geometry in the three conditions permit calculation of the variation of surface tension in the normal lung as a function of volume without assuming a specific surface area vs. volume function or a maximum surface tension. The calculated surface tension dropped during deflation from a high of 50 dyn/cm total lung capacity (TLC) to a low of 4 dyn/cm (less than 25% TLC) with the species being roughly similar. The PV behavior of Tween-surface lungs appears to fit a simple model of alveolar expansion. Air dimensions calculated for the four species on the basis of this model are ordered in the same sequence as morphological measurements, but larger in magnitude.
在三种条件下测定了切除的猫、狗、兔和大鼠肺的压力-容积（PV）曲线：1）正常表面、充气；2）充生理盐水；3）聚氧乙烯（20）山梨醇酐单月桂酸酯-（吐温20）表面、充气。由于含有2%吐温20的肺灌洗液表面张力恒定，吐温表面充气肺可能表现出表面张力恒定的肺的压力-容积行为。这些数据以及三种条件下等效几何形状的假设允许在不假设特定表面积与容积函数或最大表面张力的情况下，计算正常肺中表面张力随容积的变化。计算得出的表面张力在放气过程中从肺总量（TLC）时的50达因/厘米的高位下降到4达因/厘米（小于25%TLC）的低位，不同物种的情况大致相似。吐温表面肺的PV行为似乎符合肺泡扩张的简单模型。基于该模型计算出的四种物种的气腔尺寸顺序与形态学测量结果相同，但数值更大。
