Faculty of Medicine and Health Sciences, Department of Pharmacology, Institute of Pharmacology, Universite de Sherbrooke, Sherbrooke, QC, J1H 5N4 Canada.
Biol Chem. 2013 Mar;394(3):353-60. doi: 10.1515/hsz-2012-0295.
We recently identified a novel human B2 receptor (B2R) agonist [Hyp(3),Thi(5),(N)Chg(7),Thi(8)]-bradykinin (NG291) with greater in vitro and in vivo potency and duration of action than natural bradykinin (BK). Here, we further examined its stability and selectivity toward B2R. The hypotensive, antithrombotic, and profibrinolytic functions of NG291 relative to BK and its analogue ([Hyp(3),Thi(5),(4-Me)Tyr(8)(ΨCH(2)NH)Arg(9)]-BK) (RMP-7) were also tested. Contraction assays using isolated mouse stomachs (containing kinin B1R, B2R, and kininase I- and II-like activities) showed that NG291 is a more potent contractant than BK and is inhibited by HOE-140 (B2R antagonist) but unaffected by R954 (B1R antagonist), whereas both decreased the potency of BK. In stomach tissues from B2R knockout mice, BK maintained its activity via B1R, whereas NG291 had no contractile effect, indicating that it was selective for B2R. Unlike BK, NG291 was not degraded by rabbit lung ACE. Comparing intravenously administered BK and NG291 revealed that NG291 exhibited more potent and prolonged hypotensive action and greater antithrombotic and profibrinolytic activities. These effects were of comparable magnitude to RMP-7 and were absent in B2R knockout mice. We concluded that NG291 is a novel biostable B2R-selective agonist that may prove suitable for investigating the (pre)clinical cardioprotective efficacy of B2R activation.
我们最近发现了一种新型的人类 B2 受体（B2R）激动剂 [Hyp(3),Thi(5),(N)Chg(7),Thi(8)]-缓激肽（NG291），其体外和体内活性以及作用持续时间均优于天然缓激肽（BK）。在这里，我们进一步研究了它对 B2R 的稳定性和选择性。还测试了 NG291 相对于 BK 及其类似物（[Hyp(3),Thi(5),(4-Me)Tyr(8)(ΨCH(2)NH)Arg(9)]-BK）（RMP-7）的降压、抗血栓形成和纤维蛋白溶解功能。使用分离的小鼠胃（含有激肽 B1R、B2R 和激肽酶 I 和 II 样活性）进行的收缩测定表明，NG291 比 BK 更强效的收缩剂，并被 HOE-140（B2R 拮抗剂）抑制，但不受 R954（B1R 拮抗剂）影响，而两者均降低了 BK 的效力。在 B2R 敲除小鼠的胃组织中，BK 通过 B1R 保持其活性，而 NG291 没有收缩作用，表明其对 B2R 具有选择性。与 BK 不同，NG291 不会被兔肺 ACE 降解。比较静脉给予的 BK 和 NG291 表明，NG291 表现出更强效和更持久的降压作用以及更大的抗血栓形成和纤维蛋白溶解活性。这些作用与 RMP-7 相当，在 B2R 敲除小鼠中不存在。我们得出结论，NG291 是一种新型的生物稳定的 B2R 选择性激动剂，可能适合研究 B2R 激活的（临床前）心脏保护功效。
