Relationship between adiponectin and nitrite in healthy and preeclampsia pregnancies.

Background: Controversial results have been reported regarding plasma adiponectin levels in preeclampsia (PE) compared to healthy pregnancies (HP). Adiponectin activates eNOS, increasing the levels of the vasodilator nitric oxide (NO). PE reduces the levels of nitrite (an NO marker) and induces higher levels of ADMA (an endogenous eNOS inhibitor) compared to HP. No previous study has examined whether a positive correlation exists between adiponectin and nitrite in HP and PE and how ADMA may interfere with this correlation.

Methods: We measured plasma nitrite concentrations using an ozone-based chemiluminescence assay, and plasma ADMA and adiponectin levels using enzyme immunoassays in 117 pregnant women (70 healthy and 47 preeclamptic).

Results: We found higher adiponectin levels (23.6±13.0 vs. 17.8±5.6µg/ml; P<0.05) and lower plasma nitrite levels (104.5±84.3 vs. 177.2±151.3 nM; P<0.05) in PE compared to HP. We found a significant positive correlation between these markers in HP (r=0.3; P<0.05), but no correlation in PE. However, when we grouped PE women regarding ADMA levels (low and high levels), a strong positive correlation was found in the group with lower ADMA levels (r=0.67; P<0.05), suggesting that high ADMA concentrations may interfere with the physiological activation of eNOS by adiponectin in PE.

Conclusions: Our findings showed higher levels of adiponectin and lower nitrite levels in PE compared to HP, and these levels were positively correlated in HP and in PE presenting lower concentrations of ADMA.