Detection of C-type natriuretic peptide in fetal circulation

C-type natriuretic peptide (CNP) belongs to the natriuretic peptide family that plays an important role in the control of blood pressure, renal functi on and volume homeostasis. In contrast to the atrial natriuretic peptide an d brain natriuretic peptide, CNP acts in an autocrine/ paracrine fashion an d is considered to be the endothelial component of the natriuretic peptide system. CNP has a high expression and tissue-specific regulation in reprodu ctive organs. Using a radio-immunoassy for CNP-22 we measured for the first time CNP in fetal blood. Samples were taken by cordocentesis in a group of Fetuses with rhesus isoimmunisation (10.74 +/- 2.81 pg/ml), fetuses with r hesus isoimmunisation after intravascular transfusion (10.03 +/- 4.01 pg/ml ) and a group with structural anomalies (12.9 +/- 5.67 pg/ml). A group of h ealthy fetuses was used as controls (11.64 +/- 4.32 pg/ml). In contrast to ANP, the fetal CNP-plasma concentrations remain stable in the investigated fetal diseases and after volume load during intravascular transfusion. More over, fetal CNP-plasma levels are higher than previously measured maternal concentrations in normal pregnancies. Therefore, the fetus expresses CNP in dependently of the maternal circulation.