Perinatal pulmonary prostaglandin production

Products of reactions catalyzed by prostaglandin cyclo-oxygenase [prostaglandins (PG), thromboxanes] were analyzed by gas chromatography with electron-capture detection in the venous effluents of in situ Krebs-perfused lungs of exteriorized fetal goats and sheep before and after ventilation with air. The major products were 6-keto-PGF1 alpha and 6,15-diketo[13,14-dihydro] PGI2 without blood components. After ventilation, which decreased pulmonary vascular resistance to 63% of the before-ventilation value, lung production of 6-keto-PGF1 alpha and metabolite increased 50 and 230%, respectively. These data, in addition to earlier findings of inhibition of ventilation-induced pulmonary vasodilation by indomethacin and increased net production of PG-like material after ventilation of blood-perfused fetal lungs, support the hypothesis that ventilation of fetal lungs with air at birth increases synthesis of PGI2 by or near pulmonary resistance vessels, resulting in high local concentrations of PGI2 near its site of production. PGI2 appears to be important in the pulmonary vascular resistance decrease that is necessary for successful perinatal transition.