Vasoactive and natriuretic mediators in umbilical cord blood: A report of our observation and review of the literature

Background: The relative potency and interrelationship among vasoactive and natriuretic mediators are thought to be important in the transition from fetal to neonatal life. However, little is known about their potential roles in the perinatal setting. Aim: The aim of this study was to evaluate further the potential roles of vasoactive and natriuretic mediators in the perinatal setting. Study design: We measured umbilical venous levels of arginine vasopressin, endothelin-1, adrenomedullin, natriuretic peptides and NO₂^-/NO₃^- in 24 vaginally delivered newborns and examined their possible functions. Results: Cord levels of vasopressin, endothelin-1 and adrenomedullin were considerably higher compared with normal adult values; the concentrations were more than 10-fold higher for vasopressin, and more than threefold higher for endothelin-1 and adrenomedullin. The levels of natriuretic peptides and NO₂^-/NO₃^- were almost comparable to those of normal adults. Among the mediators, there was a significant correlation between endothelin-1 and adrenomedullin. Conclusions: It appears from other studies that the postnatal fall in vasopressin and endothelin-1 levels is associated with increased levels of natriuretic peptides and NO₂^-/NO₃^-. Based on these observations, we consider that these mediators may play active roles in the initiation, maintenance or both of the transition from fetal to neonatal life.