A non-glycosylated form of pulmonary surfactant protein A appears in rat amniotic fluid

Abstract

Surfactant protein A (SP-A) is a family of glycoproteins that have a triplet with 26, 32 and 36 kDa under reducing conditions in rat lung. We wanted to evaluate the SP-A forms in amniotic fluid of pregnant rats compared to those found in rat lungs. By Western blot analysis, glycosylated SP-A, was not found in the amniotic fluid in contrast to the pulmonary surfactant triplet SP-A, which comprises a 26 kDa protein and its glycosylated 32 and 36 kDa forms. The SP-A concentration in amniotic fluid was barely detectable at 18 days of gestation (20 +/- 12 ng.ml-1), and then increased and reached 700 +/- 333 ng.ml-1 at the final gestational day 21, as determined by an enzyme-linked immunoabsorbent assay. Immunohistochemically, SP-A was found in some epithelial cells of larger respiratory bronchi, but not, or to a lesser degree, in smaller respiratory bronchi at gestational day 18. At 21 days of gestation, SP-A was detected in bronchial and bronchiolar nonciliated epithelial Clara cells, alveolar epithelial type II cells and some alveolar macrophages. The ratio of the 26, 32 and 36 kDa SP-A forms in bronchoalveolar, bronchobronchiolar and tracheal lavage fluids prepared from adult rats was 6:29:65, 84:5:11 and 100:0:0, respectively. These findings show the presence of a non-glycosylated SP-A in rat amniotic fluid. This may reflect the increased ratio of non-glycosylated SP-A to bronchoalveolar, bronchobronchiolar and tracheal lavage fluids, respectively.

The effects of S-nitrosoglutathione and S-nitroso-N-acetyl-D, L-penicillamine in a rat model of pre-eclampsia

“…Insufficient surfactant production by the lungs can result in respiratory distress syndrome which is observed in premature and low birth weight infants. [3233]…”

Liposome-encapsulated hemoglobin (hemoglobin-vesicle) is not transferred from mother to fetus at the late stage of pregnancy in the rat model

“…Corresponding to fetal lung maturity, SP-A mRNA is first detectable in rodent fetal lung at the late stage of pregnancy and increases to term (Mendelson and Boggaram, 1991;Alcorn et al, 1999). SP-A protein in rat amniotic fluid was reported to be evident at 18 days of pregnancy and increased markedly through term Sakai et al, 1994). Since fetal lung maturation is one of the most important indicators reflecting fetal development, these data suggest that rat fetuses generally developed well during the 7 days of HbV infusion.…”