Putman E, Creuwels L A, van Golde L M, Haagsman H P
Laboratory of Veterinary Biochemistry, Utrecht University, The Netherlands.
Biochem J. 1996 Dec 1;320 ( Pt 2)(Pt 2):599-605. doi: 10.1042/bj3200599.
Separation of surfactant subtypes is now commonly used as a parameter in assessing the amount of active compared with inactive material in various models of lung injury. The protein content, morphology and surface activity were determined of the heavy and light subtype isolated by differential centrifugation. Here we report the presence of surfactant proteins B and C in the heavy subtype but not in the light subtype. Adsorption studies revealed that separation of fast adsorbing bronchoalveolar lavage resulted in slowly adsorbing heavy and light subtypes. Surfactant, reconstituted from heavy and light fractions, did not show a high adsorption rate. It is concluded that the isolation procedures might result in a loss of fast adsorbing surfactant structures. Surface area cycling was used as a model in vitro for the extracellular surfactant metabolism. The heavy subtype is converted into the light subtype during conversion. Conversion performed with resuspended heavy subtype revealed the generation of a disparate subtype. Furthermore it was found that the conversion was dependent on preparation and handling of the samples before cycling. Finally, adsorption studies at low surfactant concentrations revealed a delayed adsorption of lipid-extracted surfactants compared with natural surfactants. These observations emphasize the importance of the (surfactant-associated protein A-dependent) structural organization of surfactant lipids in the adsorption process.
目前，在评估各种肺损伤模型中活性物质与非活性物质的量时，表面活性剂亚型的分离通常被用作一个参数。通过差速离心分离出重质和轻质亚型，并测定了它们的蛋白质含量、形态和表面活性。在此我们报告，重质亚型中存在表面活性剂蛋白B和C，而轻质亚型中不存在。吸附研究表明，快速吸附的支气管肺泡灌洗物的分离产生了吸附缓慢的重质和轻质亚型。由重质和轻质组分重构的表面活性剂并未显示出高吸附率。得出的结论是，分离程序可能导致快速吸附的表面活性剂结构丧失。表面积循环被用作细胞外表面活性剂代谢的体外模型。在转换过程中，重质亚型会转变为轻质亚型。对重悬的重质亚型进行的转换显示产生了一种不同的亚型。此外，还发现转换取决于循环前样品的制备和处理。最后，在低表面活性剂浓度下的吸附研究表明，与天然表面活性剂相比，脂质提取的表面活性剂的吸附延迟。这些观察结果强调了表面活性剂脂质的（与表面活性剂相关蛋白A相关的）结构组织在吸附过程中的重要性。
