Plasma endothelin and atrial natriuretic peptide in normal and hypertensive pregnancy

To investigate the possible role of endothelin-1 (ET-1) and atrial natriuretic peptide (ANP) in the pathogenesis of pregnancy-induced hypertension (PIH).

A total of 110 normal pregnant women (in three trimesters, labour or postpartum) and 30 patients with PIH were studied by measuring plasma ET-1 and ANP levels by radioimmunoassay; 23 normal non-pregnant women were selected as controls.

Compared with normal non-pregnant women, plasma ET-1 levels were significantly decreased in normal pregnant women during all three trimesters. Plasma ET-1 level was significantly increased in the 2nd stage of labour, compared with that in the 3rd trimester. There were significant positive correlation between plasma ET-1 level and mean arterial pressure in normal non-pregnant women and normal pregnant women in all three trimesters. Compared with matched normal pregnant women, plasma ET-1 and ANP levels were significantly increased, while plasma ANP/ET-1 ratio was significantly decreased in PIH patients. Significant positive correlations existed between plasma ET-1 level and mean arterial pressure or the score index of the severity of PIH. After the treatment with magnesium sulfate infusion, plasma ET-1 and ANP levels were significantly decreased, but plasma ANP/ET-1 ratio was significantly increased in PIH patients.

Augmentation of ET-1 secretion and attenuation of ANP function may be responsible for the development of PIH. ET-1 secretion may be indirectly influenced by magnesium in PIH.