Hypoxemia inducing endothelin-1 secretion in meconium aspiration in piglets.

According to our previous study, the secretion of endothelin-1 (ET-1) was induced after meconium aspiration in piglets. In order to determine the role of hypoxemia in the ET-1 secretion during meconium aspiration, 12 piglets were randomly assigned into 2 groups: the hyperoxia and the hypoxia group (6 animals/group). Instillation of meconium (20% in normal saline) was achieved via the endotracheal tube (3 mL/kg) in all these animals. The hyperoxia group was ventilated with 100% oxygen, whereas the hypoxia group was ventilated with only 40% of oxygen. The plasma ET-1 levels, arterial blood gases and hemodynamics were measured at the baseline, 60, 120, 180, and 240 minutes after meconium instillation. The result showed plasma ET-1 levels to be significantly higher in the hypoxia group than the hyperoxia group at 180 and 240 min, respectively (p <0.05 andp <0.01). Besides, the pulmonary arterial pressures were significantly higher in the hypoxia group after 60 min (p <0.05 at 60 min and p <0.01 after 120 min). These results suggested that hypoxemia may be the major factor for inducing ET-1 secretion in meconium aspiration syndrome.