Abnormal vasoreactivity in the pathophysiology of persistent pulmonary hypertension of the newborn.

1. Describe the factors that modulate the transition of pulmonary circulation from in utero to after birth. 2. Delineate temporal changes in pulmonary vascular resistance during fetal life. 3. List the substances that play a role in vasoregulation of normal fetal pulmonary circulation. 4. Delineate the role of nitric oxide in increasing pulmonary blood flow at birth. 5. Describe the common physiologic characteristics of persistent pulmonary hypertension of the newborn. 6. Delineate how abnormalities in production and responsiveness to nitric oxide affect developing lung circulation. 7. Explain why inhaled nitric oxide therapy may not be effective in all cases of pulmonary hypertension.