Abstract
The preterm newborn lamb has high concentrations of circulating prostaglandin E2 (PGE2) that may play a role in maintaining the patency of the ductus arteriosus. PGE2 is removed rapidly from the venous circulation by the lung and is metabolized to its 15-keto metabolites by the intracellular enzyme, 15-OH prostaglandin dehydrogenase (15-OHPD). We studied the ability of the isolated, perfused lung from 100 days gestation (n=8) and near term (term is 150 days) lamb fetuses (n=10) to metabolize PGE2. After an intraaterial infusion of 3H-PGE2 and 14C-inulin (to act as a marker of extracellular space), the majority of 3H activity was cleared through the lung after the 14C activity had fallen to negligible values. The 3H activity that was retained longer in the lung was primarily associated with the 15-keto metabolites of PGE2. Lungs from immature fetal lambs metabolized 25% less PGE2 than did lungs from animals near term. 15-OHPD activity in homogenates of lamb lung is not higher near term than at 100 days. This suggests that transport processes that regulate the uptake of PGE2 into the intracellular compartment, and not 15-OHPD, may represent the limiting step in the pulmonary clearance of PGE2 in the developing lamb lung. This is consistent with our prior observation that premature lambs have decreased plasma clearance rates (in vivo) and elevated circulating concentrations of PGE2 when compared with term newborn lambs.
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Clyman, R., Heymann, M. 1270 DEVELOPMENT OF PULMONARY METABOLISM OF PROSTAGLANDIN E2. Pediatr Res 15 (Suppl 4), 655 (1981). https://doi.org/10.1203/00006450-198104001-01299
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DOI: https://doi.org/10.1203/00006450-198104001-01299