Circulating levels of endothelin and atrial natriuretic factor during postnatal life.

We determined plasma endothelin-1-like immunoreactivity and atrial natriuretic factor concentrations in preterm and full-term newborn infants during the first month of life. Plasma endothelin-1-like immunoreactivity levels were far greater than those of maternal blood in the newborn infants. The highest plasma endothelin-1-like immunoreactivity levels were observed on the first day of life (8.7 +/- 3.7 pmol/l) and gradually decreased with age. There was no significant difference in plasma endothelin-1-like immunoreactivity levels between preterm and full-term infants. A good correlation was observed between plasma endothelin-1-like immunoreactivity levels and atrial natriuretic factor concentrations (p < 0.01). These results suggest that circulating endothelin may regulate the cardiovascular system in the newborn period.