ABSTRACT
Circulating angiotensin II (AngII) does not cross the blood brain barrier. However, after injection in the circulation, AngII was shown to produce effects in the brain. For these reasons, it was hypothesized that the brain contained AngII receptors in the circumventricular organs, which are areas outside the blood brain barrier. In peripheral tissues, binding of AngII to some of its receptors has been shown to be sensitive to sulfhydryl reducing agents such as dithiothreitol. It was later revealed that these receptors belong to the AT1 subtype. Binding to brain AT1 receptors was also sensitive to sulfhydryl reducing agents. AngII receptors are expressed in large numbers in skeletal muscle and skin during late embryonic life. Most of these peripheral AngII receptors belong to the AT2 subtype, and their number decreases dramatically after birth. In addition, AT2 receptors are present in developing aortas in higher numbers than AT1 receptors.
