Agonist-dependent AT(4) receptor internalization in bovine aortic endothelial cells.
Recent studies have characterized a specific binding site for the C-terminal 3-8 fragment of angiotensin II (Ang IV). In the present study we looked at the internalization process of this receptor on bovine aortic endothelial cells (BAEC). Under normal culture conditions, BAEC efficiently internalized (125)I-Ang IV as assessed by acid-resistant binding. Internalization of (125)I-Ang IV was considerably decreased after pretreatment of cells with hyperosmolar sucrose or after pretreatment of BAEC with inhibitors of endosomal acidification such as monensin or NH(4)Cl. About 50% of internalized (125)I-Ang IV recycled back to the extracellular medium during a 2 h incubation at 37 degrees C. (125)I-Ang IV remained mostly intact during the whole process of internalization and recycling as assessed by thin layer chromatography. As expected, internalization of (125)I-Ang IV was completely abolished by divalinal-Ang IV, a known AT(4) receptor antagonist. Interestingly, (125)I-divalinal-Ang IV did not internalize into BAEC. These results suggest that AT(4) receptor undergoes an agonist-dependent internalization and recycling process commonly observed upon activation of functional receptors.
Briand
S I
SI
Department of Pharmacology, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada.
Neugebauer
W
W
Guillemette
G
G
D000804:Angiotensin II / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D006982:Hypertonic Solutions / Q000494:pharmacology; D007457:Iodine Radioisotopes; D011945:Receptors, Angiotensin / Q000819:agonists* / Q000378:metabolism*; D013395:Sucrose / Q000494:pharmacology
C090830:AT4 receptor; D057911:Angiotensin Receptor Antagonists; D006982:Hypertonic Solutions; D007457:Iodine Radioisotopes; D011945:Receptors, Angiotensin; C104765:divalinal-angiotensin IV; D000804:Angiotensin II; C012877:angiotensin II, des-Asp(1)-des-Arg(2)-Ile(5)-; D013395:Sucrose