Stimulation of cyclic GMP production via AT2 and B2 receptors in the pressure-overloaded aorta after banding.
Abdominal aortic banding induces upregulation of the angiotensin II (Ang II) type-2 (AT2) receptor, thereby decreasing the contractile response to Ang II in the thoracic aorta of the rat. The aim of this study was to use a mouse model to clarify the mechanisms by which the banding elicits upregulation of the aortic AT2 receptor and the subsequent attenuation of Ang II responsiveness. Concomitantly with the elevation in blood pressure and plasma renin concentration after banding, AT2-receptor mRNA levels in the thoracic aorta rapidly increased in mice within 4 days. Upregulation of the AT2 receptor, as well as blood pressure elevation after banding, was abolished by losartan administration. The contractile response to Ang II was depressed in aortic rings of banding mice but not of sham mice, and was restored by either the AT2-receptor antagonist PD123319 or the bradykinin B2-receptor antagonist icatibant. cGMP content in the thoracic aorta of banding mice was 9-fold greater than that of sham mice, and the elevation was reduced to sham levels 1 hour after intravenous injection of PD123319 or icatibant. When aortic rings were incubated with Ang II, cGMP content increased in banding rings but not in sham rings; the pretreatment with PD123319 or icatibant inhibited Ang II-induced cGMP production. These results suggest that aortic banding induces upregulation of the AT2 receptor through increased circulating Ang II via the AT1 receptor, thereby activating a vasodilatory pathway in vessels through the AT2 receptor via the kinin/cGMP system.
Hiyoshi
Hiromi
H
Department of Pharmacology, Faculty of Pharmaceutical Sciences and High Technology, Research Center, Kobe Gakuin University, Japan.
Yayama
Katsutoshi
K
Takano
Masaoki
M
Okamoto
Hiroshi
H
D000804:Angiotensin II / Q000097:blood / Q000502:physiology; D047228:Angiotensin II Type 1 Receptor Blockers; D057912:Angiotensin II Type 2 Receptor Blockers; D000818:Animals; D001012:Aorta, Abdominal; D001013:Aorta, Thoracic / Q000378:metabolism / Q000503:physiopathology; D001024:Aortic Valve Stenosis / Q000150:complications / Q000378:metabolism / Q000503:physiopathology*; D001920:Bradykinin / Q000031:analogs & derivatives* / Q000494:pharmacology; D065094:Bradykinin B2 Receptor Antagonists; D006152:Cyclic GMP / Q000096:biosynthesis*; D006973:Hypertension / Q000209:etiology / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D008026:Ligation; D019808:Losartan / Q000494:pharmacology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D023421:Models, Animal; D009569:Nitric Oxide / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D044140:Receptor, Angiotensin, Type 1 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D044139:Receptor, Angiotensin, Type 2 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D043782:Receptor, Bradykinin B2 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D012083:Renin / Q000097:blood; D015854:Up-Regulation; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
D047228:Angiotensin II Type 1 Receptor Blockers; D057912:Angiotensin II Type 2 Receptor Blockers; D065094:Bradykinin B2 Receptor Antagonists; D007093:Imidazoles; D011725:Pyridines; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D043782:Receptor, Bradykinin B2; D000804:Angiotensin II; C073402:PD 123319; D009569:Nitric Oxide; C065679:icatibant; D012083:Renin; D006152:Cyclic GMP; D019808:Losartan; D001920:Bradykinin