Low prostacyclin synthetase activity of fetal rat aorta. Progressive increase after birth.

Aortae from fetal or 3 weeks old rats produced very small amounts of PGI2, prostacyclin. This production increased from 4 weeks on, reaching adult values at about ten weeks. This maturation seemed to be predominantly determined by a change in the PGI2 synthetase system, rather than in arachidonic acid availability, phospholipase or cyclo-oxygenase activity. The anti-oxidant ascorbic acid stimulated prostacyclin production more strongly in adult than in young rat aortae. This finding suggests that the lower production of PGI2 by young tissues is not due to an enhanced inhibition of prostacyclin synthetase by lipid peroxides.