Circulating levels of hydrogen sulphide negatively correlate to nitrite levels in gestational hypertensive and preeclamptic pregnant women.

Endothelial dysfunction is a hallmark of preeclampsia and the role of nitric oxide (NO) has been extensively studied in this pregnancy complication. In recent years, hydrogen sulphide (H S) has arisen as a new gasotransmitter with an impact on endothelial function. However, the involvement of H S in the pathophysiology of preeclampsia is not fully understood, and only a few studies with limited sample size have investigated circulating levels of H S in preeclamptic patients. Moreover, H S levels have not been previously evaluated in gestational hypertension. Furthermore, the relationship between H S and NO in these hypertensive disorders of pregnancy has yet to be determined. We measured H S levels in plasma of 120 healthy pregnant women, 88 gestational hypertensive and 62 preeclamptic women. We also measured plasma nitrite in a subset of patients and carried out correlation analysis between plasma H S and nitrite in these three groups. We found that plasma H S was elevated in preeclampsia and further increased in gestational hypertension compared to healthy pregnancy. Plasma nitrite was reduced in gestational hypertension and preeclampsia, and these levels were negatively correlated with H S in both gestational hypertension and preeclampsia, but not in healthy pregnancy. Our results indicate that increases in H S may represent a mechanism triggered as an attempt to compensate reduced NO in gestational hypertension and preeclampsia. Future studies are warranted to investigate the mechanisms underlying H S/NO interaction on mediating endothelial dysfunction in these hypertensive disorders of pregnancy.