Mammalian lung development proceeds during the postnatal period and continues throughout life. Intricate tubular systems of airways and vessels lined by epithelial cells are developed during this process. All cells, and particularly epithelial cells, carry an array of glycans on their surfaces. N-acetylneuraminic (Neu5Ac) and N-glycolylneuraminic (Neu5Gc) acids, two most frequently-occurring sialic acid residues, are essential determinants during development and in the homeostasis of cells and organisms. However, systematic data about the presence of cell surface sialic acids in the postnatal lung and their content is still scarce. In the present study, we addressed the histochemical localization of Neu5Ac > Neu5Gc in 0-day-old rat lungs. Furthermore, both residues were separated, identified and quantified in lung membranes isolated from 0-day-old rat lungs using high-performance liquid chromatography (HPLC) methodologies. Finally, we compared these results with those previously reported by us for adult rat lungs. The Neu5Ac > Neu5Gc residues were located on the surface of ciliated and non-ciliated cells and the median values for both residues in the purified lung membranes of newborn rats were 5.365 and 1.935 μg/mg prot., respectively. Comparing these results with those reported for the adults, it was possible to observe a significant difference between the levels of Neu5Ac and Neu5Gc (p < 0.001). A more substantial change was found for the case of Neu5Ac. The preponderance of Neu5Ac and its expressive increase during the postnatal development points towards a more prominent role of this residue. Bearing in mind that sialic acids are negatively charged molecules, the high content of Neu5Ac could contribute to the formation of an anion “shield” and have a role in pulmonary development and physiology.

哺乳动物的肺发育在出生后时期进行，并持续一生。在这个过程中形成了由上皮细胞排列的气道和血管的复杂管状系统。所有细胞，尤其是上皮细胞，其表面都带有一系列聚糖。N-乙酰神经氨酸 (Neu5Ac) 和 N-羟乙酰神经氨酸 (Neu5Gc) 酸是两种最常见的唾液酸残基，是发育和细胞和生物体稳态的重要决定因素。然而，关于出生后肺中细胞表面唾液酸的存在及其含量的系统数据仍然很少。在本研究中，我们解决了 0 日龄大鼠肺中 Neu5Ac > Neu5Gc 的组织化学定位。此外，两种残留物被分离，使用高效液相色谱 (HPLC) 方法在从 0 日龄大鼠肺中分离的肺膜中鉴定和量化。最后，我们将这些结果与我们先前报告的成年大鼠肺的结果进行了比较。Neu5Ac > Neu5Gc 残留位于纤毛和非纤毛细胞表面，新生大鼠纯化肺膜中两种残留的中值分别为 5.365 和 1.935 μg/mg prot.。将这些结果与成人报告的结果进行比较，可以观察到 Neu5Ac 和 Neu5Gc 水平之间的显着差异（p < 0.001）。对于 Neu5Ac 的情况，发现了更实质性的变化。Neu5Ac 的优势及其在出生后发育过程中的表达增加表明该残留物的作用更为突出。