Distribution of surfactant proteins in type II pneumocytes of newborn, 14-day old, and adult rats:: an immunoelectron microscopic and stereological study
Distribution of surfactant proteins in type II pneumocytes of newborn, 14-day old, and adult rats:: an immunoelectron microscopic and stereological study
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DOI：
10.1007/s00418-005-0066-0
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发表时间：
2005-12-01
影响因子：
2.3
通讯作者：
Brasch, F
中科院分区：
文献类型：
--
作者：
Schmiedl, A;Ochs, M;Brasch, F
肺表面活性物质（SP）对肺表面活性物质的功能有重要影响。与人类相比，大鼠的肺在出生时还不成熟。出生后第4天开始肺泡化。出生后肺泡形成过程中SP的分布情况知之甚少。应用免疫电镜技术研究了肺泡化前、近终末、肺泡化后和成熟肺中Ⅱ型肺泡上皮细胞中SP-A、SP-D、SP-B和SP-C前体的分布。我们确定了亚细胞体积分数和相对标记指数，以获得有关优先标记的车厢和非随机性的标签。独立于肺泡化，SP的整体细胞分布是非随机的。SP-A和SP-D在小泡和多泡体（mvb）中有优先标记。SP-B和SP-C的前体位于mvb和板层体（lb）中。有没有出生后的变化，在标签的所有三个SP在这些车厢。LB中SP-B的标记强度与肺泡化过程中LB体积分数的显著增加密切相关。我们的研究结果支持的概念，出生后大鼠肺肺泡化与显着增加的SP-B含量在LB和LB的体积分数在II型肺细胞。SP-A、SP-C和SP-D的前体物质在出生后的隔室特异性分布没有变化。
Surfactant proteins (SP) have an important impact on the function of the pulmonary surfactant. In contrast to humans, rat lungs are immature at birth. Alveolarization starts on postnatal day 4. Little is known about the distribution of SP during postnatal alveolarization. By immunoelectron microscopy, we studied the distribution of SP-A, SP-D, SP-B, and precursors of SP-C in type II pneumocytes before, near the end and after alveolarization and in mature lungs. We determined the subcellular volume fractions and the relative labeling index to obtain information about preferential labeling of compartments and non-randomness of labeling. Independently of alveolarization, the overall cellular distribution of SP was non-random. A preferential labeling for SP-A and SP-D was found in small vesicles and multivesicular bodies (mvb). SP-B and precursors of SP-C were localized in mvb and lamellar bodies (lb). There are no postnatal changes in labeling for all three SP in these compartments. Labeling intensity for SP-B in lb increased in close correlation with a significant increase in the volume fractions of lb during alveolarization. Our results support the concept that postnatal alveolarization in rat lungs is associated with significant increases in the SP-B content in lb and volume fraction of lb in type II pneumocytes. The postnatal compartment-specific distribution of SP-A, precursors of SP-C and SP-D does not change.