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

Sequential changes in plasma endothelin-l (ET-l) and pulmonary hemodynamics were studied in a piglet model of meconium aspiration syndrome (MAS). Sixt een piglets were randomly divided into meconium (MEC) and normal saline (NS ) groups (8 animals/group). The animals of the MEC group were instilled wit h meconium (20% in normal saline) via an endotracheal tube (3 ml/kg), and t he 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 hem odynamics were measured at baseline and 60, 120, 180 and 240 min after inst illation. The results showed that plasma ET-1 level of the MEC group was si gnificantly 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, pulmona ry 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 th at elevation of ET-1, which has long-lasting vasoconstriction effect, may p lay an important role of pulmonary hypertension of MAS.