ATRIAL-NATRIURETIC-PEPTIDE BINDING IN RAT PLACENTA, YOLK-SAC, DECIDUA, AND MATERNAL PLACENTAL VESSELS

Using in vitro autoradiography, binding sites of I-125-ANP (atrial nat riuretic peptide) were localized in the rat placenta, visceral yolk sa c, and decidua at 16, 18, and 20 days of gestation. There was diffuse binding over the labyrinthine region of the placenta and an intense bi nding over the decidual gland and visceral yolk sac. In the yolk sac, ANP localized over the cores of the villi where it may be involved wit h the regulation of transport across the membranes or the flow of bloo d through the vitelline vessels. Of particular interest was binding ov er the maternal blood vessels supplying the decidual region and placen ta. Receptors were located on the endothelial cells and smooth muscle cells of the arteries and veins, indicating that ANP may be involved w ith regional regulation of blood flow to the placenta.