Meconium aspiration syndrome (MAS) disrupts perinatal decreases in pulmonary vascular resistance (PVR) and is the commonest cause of neonatal pulmonary hypertension. The contribution of the potent vasoactive agent urotensin-II (U-II), in the pathophysiology of this condition, is unknown. In a new perinatal model of MAS, we combined measurement of circulating U-II levels with U-II receptor blockade studies. Nineteen anesthetized lambs were instrumented then randomly allocated to the following groups: 1) control (n = 5), 2) control plus specific U-II receptor blockade with palosuran (n = 5), 3) tracheal instillation of meconium (n = 5), 4) meconium instillation plus palosuran (n = 4). Hemodynamics, PVR, and plasma U-II were measured for 6 h after delivery. After birth in controls, U-II increased (p < 0.05), and PVR fell (p = 0.01) and this fall was prevented by U-II receptor blockade. By contrast, meconium lambs displayed a greater rise in U-II levels (p < 0.05 versus control) with an increase in PVR (p < 0.005) that was attenuated by U-II receptor blockade (p < 0.001). These findings suggest that U-II normally acts as a pulmonary vasodilator after birth, but in the presence of MAS, it assumes a vasoconstrictor role. U-II receptor blockade also improves pulmonary hemodynamics in this model. Copyright © 2010 International Pediatric Research Foundation, Inc.
CITATION STYLE
Simpson, C. M., Smolich, J. J., Shekerdemian, L. S., & Penny, D. J. (2010). Urotensin-II contributes to pulmonary vasoconstriction in a perinatal model of persistent pulmonary hypertension of the newborn secondary to meconium aspiration syndrome. Pediatric Research, 67(2), 150–157. https://doi.org/10.1203/PDR.0b013e3181c345ea
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