Discrepancy between phase behavior of lung surfactant phospholipids and the classical model of surfactant function.
Discrepancy between phase behavior of lung surfactant phospholipids and the classical model of surfactant function.
复制标题
肺表面活性剂磷脂的相行为与表面活性剂功能的经典模型之间的差异。
DOI：
10.1016/s0006-3495(01)75865-1
复制
发表时间：
2001
影响因子：
3.4
通讯作者：
Hall,SB
中科院分区：
文献类型：
--
作者：
Piknova,B;Schief,WR;Vogel,V;Discher,BM;Hall,SB
这里报道的研究使用荧光显微镜和布鲁斯特角显微镜来测试肺表面活性剂如何形成在肺部高表面压力下亚稳定的薄膜的经典模型。该模型预测功能膜是液体凝结的 (LC)，并且富含二棕榈酰磷脂酰胆碱 (DPPC)。两种显微方法均表明，在含有来自小牛表面活性剂的全套磷脂的单分子层中，在表面压力接近 70mN/m 时，膨胀相与凝聚域持续共存。超过 45mN/m 时，成分会从界面塌陷，但两相的相对面积变化不大，LC 相所占界面的比例从未超过 30%。基于这些发现和在捕获气泡的连续界面上获得的等温线的计算估计，其他成分的崩溃使 DPPC 的摩尔分数增加到不高于 0.37。我们得出的结论是，含有全套磷脂的单分子层可实现高表面压力，但不会形成均匀的 LC 薄膜，并且其混合成分远远低于之前预测的近乎纯的 DPPC。这些发现与经典模型相矛盾。
The studies reported here used fluorescence microscopy and Brewster angle microscopy to test the classical model of how pulmonary surfactant forms films that are metastable at high surface pressures in the lungs. The model predicts that the functional film is liquid-condensed (LC) and greatly enriched in dipalmitoyl phosphatidylcholine (DPPC). Both microscopic methods show that, in monolayers containing the complete set of phospholipids from calf surfactant, an expanded phase persists in coexistence with condensed domains at surface pressures approaching 70mN/m. Constituents collapsed from the interface above 45mN/m, but the relative area of the two phases changed little, and the LC phase never occupied more than 30% of the interface. Calculations based on these findings and on isotherms obtained on the continuous interface of a captive bubble estimated that collapse of other constituents increased the mol fraction of DPPC to no higher than 0.37. We conclude that monolayers containing the complete set of phospholipids achieve high surface pressures without forming a homogeneous LC film and with a mixed composition that falls far short of the nearly pure DPPC predicted previously. These findings contradict the classical model.