In the placentomes, we found a predominance of AT2 receptors. The highest proportion of AT1 receptors, determined by Ang II receptor binding studies, was found at the beginning of the gestation. However, autoradiography showed that the AT1 receptors were placed mostly on the maternal side, whereas the AT2 receptors predominated on the fetal side. In the early placentome, no stalk has developed to indicate a natural border towards the endometrium. Our finding of a higher proportion of AT1 receptors in the first part of gestation probably reflects a higher content of maternal tissue in the early placentomes.
Previous studies showed that Ang II stimulated angio-genesis and regulated uteroplacental blood-flow. Autoradiography showed very little 125I-[Sar1-Ile5-Ile8]-Ang II binding in either arteries or minor blood vessels in the bovine placenta. Ang II, however, may still exert such effects in the vasculature of the bovine placenta, since a low density of Ang II receptors does not exclude an even marked effect of Ang II. buy levaquin online
Active renin concentrations in the bovine placenta were either undetectable or low throughout the gestation.