Tracing surfactant transformation from cellular release to insertion into an air-liquid interface
Tracing surfactant transformation from cellular release to insertion into an air-liquid interface
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DOI：
10.1152/ajplung.00342.2003
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发表时间：
2004-05-01
影响因子：
4.9
通讯作者：
Putz, G
中科院分区：
文献类型：
--
作者：
Haller, T;Dietl, P;Putz, G
肺表面活性物质是由肺泡II型细胞分泌的富含脂质的致密排列的板层体样颗粒(LBPS)。释放的LBPS的颗粒性可能是结构和/或热力作用的结果。因此，必须存在促进它们转变为职能单位的机制。为了进一步确定这些机制，我们开发了跟踪LBPS的方法，从培养细胞释放LBPS到插入气液界面。当发布时，LBPS经历了结构转换，但没有分散，通常会保留几天的球形外观。然而，它们能够改变表面张力，并在用毛细管表面测定仪测量时显示出高的表面活性。通过荧光成像显微镜对插入气液界面的LBPS进行分析，发现它们发生了显著的结构转变。这些事件是瞬间发生的，但当界面已经被先前转化的物质占据时或当表面张力已经很低时，这些事件就停止了。这些结果表明，LBP转变的驱动力是由作用在这些颗粒上的内聚力和拉力决定的。他们进一步表明，LBPS的转化是一个自我调节的界面过程，很可能不需要结构中间体或酶激活。
Pulmonary surfactant is secreted by alveolar type II cells as lipid-rich, densely packed lamellar body-like particles (LBPs). The particulate nature of released LBPs might be the result of structural and/or thermodynamic forces. Thus mechanisms must exist that promote their transformation into functional units. To further define these mechanisms, we developed methods to follow LBPs from their release by cultured cells to insertion in an air-liquid interface. When released, LBPs underwent structural transformation, but did not disperse, and typically preserved a spherical appearance for days. Nevertheless, they were able to modify surface tension and exhibited high surface activity when measured with a capillary surfactometer. When LBPs inserted in an air-liquid interface were analyzed by fluorescence imaging microscopy, they showed remarkable structural transformations. These events were instantaneous but came to a halt when the interface was already occupied by previously transformed material or when surface tension was already low. These results suggest that the driving force for LBP transformation is determined by cohesive and tensile forces acting on these particles. They further suggest that transformation of LBPs is a self-regulated interfacial process that most likely does not require structural intermediates or enzymatic activation.