Autoradiographic analysis and regulation of angiotensin receptor subtypes AT4, AT1, and AT(1—7) in the kidney

Abstract

Receptor autoradiography revealed that angiotensin AT4 receptors were abundantly expressed in normal mammalian (mouse, rat, gerbil, guinea pig, rabbit) and avian (sparrow, chicken, turkey) kidneys and were more extensively distributed than previously reported (including proximal and distal segments of the nephron, interstitium, renal artery, vein, and ureter). Angiotensin AT4 receptors were generally found to be more abundant than angiotensin AT1 receptors in mammalian kidneys, whereas angiotensin AT(1—7) receptors were not detected in either mammalian or avian kidneys. Rats subjected to various chronic treatments were found to preferentially decrease kidney AT4 receptor density (furosemide, puromycin aminonucleoside, nitro-l-arginine methyl ester), decrease kidney AT1 receptor density (bilateral ureteral obstruction), or increase kidney AT1 receptor distribution in the inner medulla (water diuresis). These results indicate that the AT4 receptor can be expressed in numerous cell types within the normal kidney of several species. Furthermore, several models of renal dysfunction and injury have been identified that selectively alter kidney AT4 density and may potentially aid in elucidating the role of this novel angiotensin receptor system in renal function.