Role of internalization in AT(1A) receptor function in proximal tubule epithelium

through angiotensin type I (AT1) receptors on apical and basolateral surfaces of proximal tubule epithelial cells, in-creases sodium reabsorption in proximal tubules. Apical and basolateral receptors internalize after exposure to ANG II, but the role of internalization in receptor signaling and transport is not well defined. To determine the role of recep-tor internalization in ANG II-mediated receptor signaling and sodium transport, we stably expressed full-length and truncated AT1A receptors in opossum kidney cells. After stimulation with ANG II, wild-type receptors on apical and basolateral surfaces rapidly internalized, inhibited adenylate cyclase, and increased transcellular sodium transport. Trun-cation of the cytoplasmic tail of the AT1A receptor (TL314) resulted in receptors that were expressed on apical and basolateral surfaces but did not internalize, inhibit adenylat