Change of adrenomedullin concentrations in plasma and amniotic fluid, and human placental adrenomedullin expression with advancing gestation

In order to characterize the expression of adrenomedullin during pregnancy, we measured the mature and total concentrations in maternal plasma and amn iotic fluid, and examined its expression in fetoplacental tissues. Plasma s amples were obtained from 13 normal normotensive non-pregnant women and 14 normal normotensive post partum women. Maternal plasma and amniotic fluid s amples were obtained from 37 normal pregnant women (10 in the first trimest er, 13 in the second trimester and 14 in the third trimester). Fetoplacenta l tissues were obtained from first and third-trimester pregnancies, Mature and total adrenomedullin concentrations in plasma and amniotic fluid were d etermined by using specific radioimmunoassay. The distribution and expressi on of adrenomedullin were determined using immunohistochemistry, reverse-tr anscriptase polymerase chain reaction, and in situ hybridization. Plasma to tal adrenomedullin concentrations were increasing with advancing gestation. The mature/total adrenomedullin ratio in the second trimester was the high est during pregnancy. Mature and total adrenomedullin concentrations in the amniotic fluid were significantly higher than those in the maternal plasma throughout gestation (P<0.05). Mature adrenomedullin concentrations and th e mature/total adrenomedullin ratio in the amniotic fluid increased with ad vancing gestation. There was a significant linear correlation between amnio tic fluid and maternal plasma mature/total adrenomedullin ratio in the firs t or second trimester of pregnancy. Adrenomedullin mRNA was identified in t he amniotic membrane and chorionic villi, and within the endothelial layers of villous blood vessels. These results suggest that the mature/total adre nomedullin ratio is modified in maternal plasma and amniotic fluid with adv ancing gestation. (C) 2001 Harcourt Publishers Ltd.