Schellhase D E, Emrie P A, Fisher J H, Shannon J M
Department of Pediatrics, University of Colorado Health Sciences Center, Denver 80262.
Pediatr Res. 1989 Sep;26(3):167-74. doi: 10.1203/00006450-198909000-00001.
Content of the 26-38-kD surfactant apoprotein (SP-A) was determined in lung homogenates from fetal (17-21 d gestation), postnatal (1-28 d of life), and adult male and female rats by a double sandwich ELISA. Expression of mRNA for SP-A as well as the hydrophobic apoproteins, SP-B and SP-C, were also determined in lung homogenates from fetal and adult rats of both sexes by Northern blot analysis. SP-A was undetectable in fetal lungs on d 17 (day of birth = d 22) and barely detectable on d 18. On d 19 there was a 3- to 4-fold increase in SP-A content above d 18 levels. Between d 19 and 21 SP-A content significantly increased another 6- to 9-fold. SP-A content on the day of birth was not significantly different from that seen on gestational d 21. SP-A content decreased 35-40% between the day of birth and postnatal d 7. After the second postnatal week SP-A content gradually increased, reaching adult levels after d 28. No sex differences in SP-A content were observed during fetal or postnatal lung maturation. SP-A mRNA was first detected in fetal lungs on d 18 and increased in relative abundance until d 21, but remained below adult levels. Developmental changes in fetal lung SP-A content closely paralleled changes in fetal expression of SP-A mRNA. SP-B mRNA was also first detected on d 18, then increased in relative abundance to adult levels by d 20. SP-C mRNA was clearly detectable on d 17, then increased in relative abundance to adult levels by d 20-21. Unlike surfactant phospholipids, there are no apparent sex differences in the expression of any of the surfactant apoproteins during late gestation. The differences observed during fetal lung maturation in the time of onset and changes in relative abundance among the three apoprotein mRNA imply that their genes may be differentially regulated in the developing rat lung.
采用双夹心酶联免疫吸附测定法（ELISA），测定了胎鼠（妊娠17 - 21天）、新生鼠（出生后1 - 28天）以及成年雄性和雌性大鼠肺匀浆中26 - 38kD表面活性物质载脂蛋白（SP - A）的含量。通过Northern印迹分析，还测定了胎鼠和成年雌雄大鼠肺匀浆中SP - A以及疏水载脂蛋白SP - B和SP - C的mRNA表达。在出生第17天（出生日为第22天）的胎肺中未检测到SP - A，第18天仅勉强检测到。第19天，SP - A含量比第18天水平增加了3至4倍。在第19天至21天之间，SP - A含量又显著增加了6至9倍。出生当天的SP - A含量与妊娠第21天所见无显著差异。出生当天至出生后第7天，SP - A含量下降了35 - 40%。出生后第二周后，SP - A含量逐渐增加，在第28天后达到成年水平。在胎肺或出生后肺成熟过程中，未观察到SP - A含量的性别差异。SP - A mRNA在胎肺中于第18天首次检测到，相对丰度持续增加直至第21天，但仍低于成年水平。胎肺中SP - A含量的发育变化与SP - A mRNA在胎肺中的表达变化密切平行。SP - B mRNA也在第18天首次检测到，然后相对丰度增加，到第20天达到成年水平。SP - C mRNA在第17天可清晰检测到，然后相对丰度增加，到第20 - 21天达到成年水平。与表面活性物质磷脂不同，在妊娠后期，任何一种表面活性物质载脂蛋白的表达均无明显性别差异。在胎肺成熟过程中观察到的三种载脂蛋白mRNA起始时间和相对丰度变化的差异表明，它们的基因在发育中的大鼠肺中可能受到不同的调控。
