Bovine aortic endothelial cells contain an angiotensin-(1-7) receptor.
Angiotensin-(1-7) is a novel peptide of the renin-angiotensin system that counteracts the pressor and proliferative responses to angiotensin II. We now report that cultured bovine aortic endothelial cells contain a saturable, high-affinity [125I]angiotensin-(1-7) binding site with an affinity of 19.3 +/- 10.7 nmol/L and a density of 1351 +/- 710 fmol/mg protein. Angiotensin-(1-7) competed at a second lower-affinity site, with an IC50 of 2.9 mumol/L. The high-affinity angiotensin II receptor antagonist sarcosine1-isoleucine8-angiotensin II blocked [125I]angiotensin-(1-7) binding to bovine aortic endothelial cells at both a high- (IC50 = 1.3 nmol/L) and a low-affinity (IC50 = 6.2 mumol/L) binding site. In contrast, D-alanine7-angiotensin-(1-7) completely blocked [125I]angiotensin-(1-7) binding, with an IC50 of 19.8 nmol/L, suggesting that D-alanine7-angiotensin-(1-7) may selectively block responses to angiotensin-(1-7) in endothelial cells. Neither the AT1 antagonist losartan nor the AT2 antagonist PD 123319 exhibited significant competition for [125I]angiotensin-(1-7) binding to endothelial cells isolated from bovine aorta, in agreement with the absence of detectable mRNAs encoding typical angiotensin receptor subtypes 1 or 2 (AT1 or AT2). Angiotensin II also competed for [125I]angiotensin-(1-7) binding to bovine aortic endothelial cells; however, the relative affinity was 13-fold lower than angiotensin-(1-7), suggesting a preference for angiotensin-(1-7) over angiotensin II. These results demonstrate that bovine aortic endothelial cells contain a unique non-AT1, non-AT2 angiotensin receptor that preferentially binds angiotensin-(1-7).
Tallant
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EA
Hypertension Center, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157-1032, USA.
Lu
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Weiss
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Chappell
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Ferrario
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D000803:Angiotensin I; D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D004730:Endothelium, Vascular / Q000737:chemistry* / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000032:analysis* / Q000378:metabolism
D010446:Peptide Fragments; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D000804:Angiotensin II; D000803:Angiotensin I; C118790:angiotensin I (1-7)