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Evidence for a novel angiotensin II receptor involved in angiogenesis in chick embryo chorioallantoic membrane

Item Type:Article
Title:Evidence for a novel angiotensin II receptor involved in angiogenesis in chick embryo chorioallantoic membrane
Creators Name:Le Noble, F.A. and Schreurs, N.H. and van Straaten, H.W. and Slaaf, D.W. and Smits, J.F. and Rogg, H. and Struijker-Boudier, H.A.
Abstract:Angiotensin II acts as a growth factor in the cardiovascular system and has been implicated in angiogenesis. The existence of at least two types of angiotensin II receptors, the AT1 and the AT2 receptors, has been suggested by ligand binding studies. We used three different AT receptor antagonists to study the receptor mediating angiotensin II-induced angiogenesis in the chorioallantoic membrane (CAM) of the chick embryo. Angiotensin II caused pronounced angiogenesis of pre- and postcapillary vessels of 30-40%. This response could only be blocked by adding the peptidergic AT2 antagonist CGP-42112A. The nonpeptidergic AT2 antagonist PD123319 and AT1 antagonist losartan (DuP 753) were not effective. In addition, we used radioligand binding studies with a range of ligands to define the nature of the receptor. Our results show a high density of specific single class AT receptor with a total number of binding sites of 1,190 fmol/mg protein and an affinity constant for angiotensin II of 2.7 nM. The inhibitory concentrations (IC50) for CGP-42112A, PD 123319 and losartan were 724, > 100,000, and 59,000 nM, respectively. Our studies suggest that these binding sites act as receptors for angiotensin II-induced angiogenesis. Both functional and radioligand binding studies suggest that the receptor is different from the classical mammalian AT1 and AT2 receptors.
Keywords:Allantois, Angiotensin II, Blood Vessels, Chick Embryo, Chorion, Embryonic and Fetal Development, Ligands, Receptors, Angiotensin, Regression Analysis, Animals, Chickens
Source:American Journal of Physiology
ISSN:0002-9513
Publisher:American Physiological Society (U.S.A.)
Volume:264
Number:2 Pt 2
Page Range:R460-R465
Date:February 1993
Official Publication:http://ajpregu.physiology.org/cgi/content/abstract/264/2/R460
PubMed:View item in PubMed

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