Tight binding of the angiotensin AT(1) receptor antagonist.
Angiotensin II induces angiotensin AT(1) receptor internalization via Clathrin coated pits formation. We investigated whether insurmountable inhibition by the non-peptide antagonist 2-ethoxy-1-[(2'-(1H-tetrazol-5-yl) biphenyl-4-yl) methyl]-1H-benzimidazoline-7-carboxylic acid (candesartan) was related to receptor internalization. Mild acid treatment can discriminate between internalized and cell surface bound [(3)H]angiotensin II. In contrast, it provides no information about the subcellular localization of bound [(3)H]candesartan since this binding is acid resistant. The internalization of [(3)H]angiotensin II is rapidly inhibited in the presence of 0.4 M sucrose. Yet, no such rapid effect was noticed for [(3)H]candesartan. [(3)H]candesartan displays insurmountable/long lasting binding to the vast majority of both wild type and L(314) truncated rat angiotensin AT(1A) receptors with impaired receptor internalization. In agreement with previously published AT(1) angiotensin receptor visualization experiments, the present data suggest that non-peptide antagonist-angiotensin AT(1) receptor complexes remain at the cell surface. Insurmountable antagonism of candesartan is therefore independent from receptor internalization via clathrin-coated pits.
Fierensa
F L
FL
Department of Molecular and Biochemical Pharmacology, Institute for Molecular Biology, Free University of Brussels, Paardenstraat 65, B-1640, Sint-Genesius Rode, Belgium. ffierens@vub.ac.be
Vanderheyden
P M
PM
Roggeman
C
C
De Backer
J
J
Thekkumkara
T J
TJ
Vauquelin
G
G
D000804:Angiotensin II / Q000378:metabolism*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001562:Benzimidazoles / Q000494:pharmacology*; D001692:Biological Transport; D001713:Biphenyl Compounds; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D004705:Endocytosis / Q000187:drug effects; D017353:Gene Deletion; D007295:Inositol Phosphates / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin / Q000378:metabolism; D013777:Tetrazoles / Q000494:pharmacology*; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
D057911:Angiotensin Receptor Antagonists; D000959:Antihypertensive Agents; D001562:Benzimidazoles; D001713:Biphenyl Compounds; D007295:Inositol Phosphates; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D013777:Tetrazoles; D014316:Tritium; D000804:Angiotensin II; C081643:candesartan; D013936:Thymidine