Increased circulating cell-free hemoglobin levels reduce nitric oxide bioavailability in preeclampsia

Area of Science:

• Obstetrics and Gynecology
• Cardiovascular Physiology
• Biochemistry

Background:

• Reduced nitric oxide (NO) bioavailability is implicated in preeclampsia pathophysiology.
• The role of increased NO consumption by cell-free hemoglobin in preeclampsia remains unexplored.

Purpose of the Study:

• To investigate the association between cell-free hemoglobin, NO consumption, and NO bioavailability in preeclampsia.
• To compare NO bioavailability markers between healthy pregnant women and those with preeclampsia.

Main Methods:

• Plasma and whole blood nitrite concentrations were measured using chemiluminescence.
• Plasma NO consumption (pNOc), plasma hemoglobin (pHb), and ceruloplasmin levels were assessed in 82 women (38 healthy, 44 preeclamptic).

Main Results:

• Preeclamptic women exhibited lower whole blood and plasma nitrite levels (-48% and -39%, respectively).
• Plasma from preeclamptic women showed 63% higher NO consumption and 53% higher pHb levels.
• Significant positive correlation between pHb and pNOc, and negative correlations between pHb/pNOc and nitrite levels were observed.

Conclusions:

• Elevated plasma hemoglobin levels contribute to increased NO consumption in preeclampsia.
• Increased NO consumption by cell-free hemoglobin reduces NO bioavailability in preeclamptic pregnancies.