The postnatal changes in red blood cell NO levels.

Aim: To determine the levels of RBC HbSNO and HbFe(II)NO using chemiluminescence in very low birth weight infants breathing room air, during the first 2 days of life.

Method: RBC NO values were compared to the levels obtained in cord blood at birth from infants of similar gestational age. Five infants ranging from 25 to 27 weeks of gestation were sampled between 12 and 24 h after birth. These infants were considered as the postnatal group and had normal blood gases at room air.

Results: The HbSNO levels were increased in the postnatal group from 49.0 +/- 17.4 nm to 152.3 +/- 54.3 nm (p = 0.0006). There was no difference in HbFe(II)NO levels between the two groups (mean of 267.6 +/- 186.5 nm in cord blood and 180.3 +/- 89.2 nm in the postnatal sample.

Conclusion: The increase in HbSNO postnatally could be an important mechanism for the neonatal pulmonary adaptation to extra-uterine life.