Effect of meconium aspiration on plasma endothelin-1 level and pulmonary hemodynamics in a piglet model.

Sequential changes in plasma endothelin-1 (ET-1) and pulmonary hemodynamics were studied in a piglet model of meconium aspiration syndrome (MAS). Sixteen piglets were randomly divided into meconium (MEC) and normal saline (NS) groups (8 animals/group). The animals of the MEC group were instilled with meconium (20% in normal saline) via an endotracheal tube (3 ml/kg), and the animals of the NS group instilled with the same amount of normal saline. The plasma ET-1 as well as pulmonary mechanics, arterial blood gas and hemodynamics were measured at baseline and 60, 120, 180 and 240 min after instillation. The results showed that plasma ET-1 level of the MEC group was significantly higher after meconium aspiration as compared with NS group (p < 0.05 at 60 and 120 min, p < 0.01 at 180 and 240 min). Furthermore, pulmonary vascular resistance (PVR) increased and remained elevated after 120 min (p < 0.01) and pulmonary artery pressure (PAP) increased after 180 min (p < 0.01). The correlation was significant between ET-1 and PVR (r = 0.92, p < 0.001) as well as ET-1 and PAP (r = 0.89, p < 0.001). These data suggest that elevation of ET-1, which has long-lasting vasoconstriction effect, may play an important role of pulmonary hypertension of MAS.