Progressive lung and cardiac changes associated with pulmonary hypertension in the fetal rat

To determine the natural history of lung vascular remodeling and cardiac changes in the rat model of persistent pulmonary hypertension syndrome (PPHN) of the newborn, we studied fetal rats subjected to maternal indomethacin administration initiated on day 19 of gestation and continued for 2, 3, or 4 days. Animals receiving a similar volume of water or alcohol served as controls. Significant pulmonary hypertension was noted in the experimental group, as evidenced by a significantly increased right to left ventricular wall ratio to 1.6 ± 0.1 in the 4‐day treatment group, as compared with 1.2 ± 0.4 in the control group (P