Prostaglandin I2 (prostacyclin) formation in lung tissues of Swiss mice.

The indirect assessment of prostacyclin synthetase by analysis of prostaglandin I2 (PGI2) formation in lung tissues of fetal, newborn and adult Swiss mice was determined by in vitro platelet inhibition. PGI2 was synthesized in fetal, newborn and adult mice lung tissues. A progressive increase in PGI2 synthesis with increasing fetal age was shown. The 11 to 13 days fetal age samples gave PGI2 values of 12.0 and 20 ng per 50 mg lung tissue, respectively. These represented 20% and 33% of the adult mean value of 60 ng. Adult levels of PGI2 were attained in utero at fetal age of 16 days. It is suggested that because of its early appearance in fetal life in the lung tissue, prostacyclin synthetase is an important enzyme in prostaglandin metabolism in the ontogeny of the fetus.