AI Article Synopsis
- Phospholipase A2 activity was measured in different lung fractions of fetal, neonatal, and adult rabbits, with a notable decrease in activity from day 24 to 28 of gestation, followed by a significant increase in newborns.
- The adult lungs exhibited lower phospholipase A2 activity compared to neonatal values, while total enzyme activity increased in all fractions except lamellar bodies in neonates.
- The study suggests that although phospholipase A2 is not directly involved in disaturated phosphatidylcholine synthesis during fetal development, it plays an important role in its production after birth.
Article Abstract
Phospholipase A2 activity was determined in subcellular fractions and lamellar bodies of fetal, neonatal and adult rabbit lungs. Specific activity in most fractions decreased from the 24th to the 28th day of gestation. All fractions except the mitochondrial and the nuclear fractions exhibited a sharp increase in activity in the newborn lung. Specific activity in the adult lung generally declined in comparison to neonatal values. During gestation total enzyme activity per gram of lung was concentrated in the cytosolic fraction. With the exception of the lamellar body fraction, the total content of phospholipase A2 activity increased dramatically in all fractions from the neonatal lung. The lamellar body fractions displayed both low specific activity and low total enzyme activity during gestation. Specific activity increased dramatically in the neonatal and adult lung but still accounted for only a small fraction of the activity in comparison to the other subcellular fractions. The subcellular content of disaturated phosphatidylcholine (PC) appeared to correlate well with the activity of phospholipase A2 in the neonatal mitochondrial, microsomal and cytosolic fractions. Since decreasing prenatal enzyme levels are associated with increasing disaturated PC content, the alkaline and calcium-dependent phospholipase A2 may not be directly involved in disaturated PC synthesis in the fetus. However, postnatally, the correlation between the pattern of production of disaturated PC and the activity of the phospholipase A2 indicates a role for this enzyme in surfactant-related disaturated PC synthesis.
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| http://dx.doi.org/10.1016/0005-2760(87)90172-x | DOI Listing |
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