Nitric oxide/endothelin-1 in preeclampsia.

BACKGROUND: Preeclampsia is characterized by vasospasm, multiple organ hypoperfusion and endothelial cell damage. Many of its signs and symptoms can be explained by an imbalance in the vasomotor tone-regulating factors, including nitric oxide (NO) and endothelin-1 (ET-1).
METHODS: Plasma samples of 59 women (20 healthy nonpregnant (NP), 20 normotensive pregnant (NTP) and 19 preeclamptic pregnant (PEP) women) were investigated by means of nitrite (NO(2)(-))/nitrate (NO(3)(-)) (two end products of nitric oxide metabolism) and endothelin-1 values.
RESULTS: PEP, when compared with NP and NTP, showed a significant increase in the plasma nitrite/nitrate and endothelin-1 concentrations. There was a weak but significant correlation between the nitrite/nitrate and endothelin-1 concentrations in the NP and NTP groups (r(1)=0.46, P<0.05, and r(2)=0.38, P<0.05, respectively) which probably revealed the balance between these vasoactive factors. In PEP, no significant correlation between nitrite/nitrate and endothelin-1 was found. Increased nitric oxide production could be the compensation against the vasoconstriction and hypertension in preeclampsia.
CONCLUSIONS: A lack of correlation between nitrite/nitrate and endothelin-1 probably indicates that in preeclampsia, a primary defense mechanism of the compensatory nitric oxide may be lost.