Angiotensin II: a releaser of PGI2 from fetal and newborn rabbit lungs.

Angiotensin II (AII) induces generation of prostacyclin (PGI2) in rabbit lung in vitro at different ages, i.e., fetus, newborn and adult. Particularly, neonatal rabbit lungs display a pattern of sensitivity to AII in producing PGI2, measured as 6-oxo-PGF1 alpha, which seems to be higher than that observed in fetal lungs. The PGI2 release appears to be specific for AII stimulation since the vasoconstriction induced by noradrenaline and ergotamine was not associated with generation of this lipidic material. The inability of PGI2 to relax the extralobar pulmonary artery in the newborn suggests that the lung microcirculation is the most likely site where the vasodilating and antiaggregatory functions of PGI2 may have a physiological role.