[Immunoradiometric determination of total and active renin in human fetal appendages]

The total renin and active renin in human fetal appendices were determined by an immunoradiographic assay. In addition, some samples of maternal plasma were analyzed in order to provide a reference value. The prorenin level was determined by subtracting the level of active renin from that of the total renin. At the end of this study, it was found that the mean total renin concentration was 515 +/- 54 pg/ml in the peripheral blood of the woman who had given birth, 30,385 +/- 2,951 pg/g in the tissue of the chorion and 3,986 +/- 822 pg/g in the amnion. The level within the placenta reached 1,113 +/- 155 pg/g of tissue in the chorionic plate, 256 +/- 53 pg/g in the villosities and 294 +/- 46 pg/g in the basal plate. In these various tissues, prorenin accounted for over 80% of the total renin, except in the chorionic villosities, where it accounted for only 72.44%. In general, this study showed that the highest, concentrations of immunoreactive renin are found in the chorionic membrane. This membrane probably plays a decisive role in regulating the renin-angiotensin system within the fetal appendices.