Biological Functions of Angiotensin and Its Receptors

Angiotensin receptors are present in a number of organs and systems including heart, kidney, gonad, and placenta; pituitary and adrenal glands; the peripheral vessels, and the central nervous system. This octapeptide exerts diverse effects that include induction of cell hypertrophy and/or hyperplasia and a stimulation of hormone synthesis and ion transport in the heart, kidney, and adrenal, primarily through type 1 (AT1) receptors. In the kidney, several heterogeneous cell populations--endothelial, epithelial, and vascular--carry AT1 receptors. Some studies suggest that AT2 receptors are also functional, but the cell type carrying this receptor and the nature of its specific function have not been fully elucidated. Although studies indicate that AT1 receptors are affected in response to physiological and pathophysiological manipulations, the functional significance of these modulations remains largely uncertain. Nevertheless, recent human genetic studies indicate that polymorphisms in AT1 receptors, as well as in other angiotensin-related genes, have significant impact on organ remodeling processes of the heart and the kidney.