Bergaya Sonia, Hilgers Rob H P, Meneton Pierre, Dong You, Bloch-Faure May, Inagami Tadashi, Alhenc-Gelas François, Lévy Bernard I, Boulanger Chantal M
Institut National de la Santé et de la Recherche Médicale, Unit 541, Hôpital Lariboisière, Paris, France.
Circ Res. 2004 Jun 25;94(12):1623-9. doi: 10.1161/01.RES.0000131497.73744.1a. Epub 2004 May 6.
The vascular kallikrein-kinin system contributes to about one third of flow-dependent dilation in mice carotid arteries, by activating bradykinin B2 receptors coupled to endothelial nitric oxide (NO) release. Because the bradykinin/NO pathway may mediate some of the effects of angiotensin II AT2 receptors, we examined the possible contribution of AT2 receptors to the kinin-dependent response to flow. Changes in outer diameter after increases in flow rate were evaluated in perfused arteries from wild-type animals (TK+/+) and in tissue kallikrein-deficient mice (TK-/-) in which the presence of AT2 receptor expression was verified. Saralasin, a nonselective angiotensin II receptor antagonist, impaired significantly flow-induced dilation in TK+/+, whereas it had no effect in TK-/- mice. In both groups, blockade of AT1 receptors with losartan or candesartan did not affect the response to flow. Inhibition of AT2 receptors with PD123319 reduced significantly flow-induced dilation in TK+/+ mice, but had no significant effect in TK-/- mice. Combining PD123319 with the bradykinin B2 receptor antagonist HOE-140 had no additional effect to AT2 receptor blockade alone in TK+/+ arteries. Flow-dependent-dilation was also impaired in AT2 receptor deficient mice (AT2-/-) when compared with wild-type littermates. Furthermore, HOE-140 significantly reduced the response to flow in the AT2+/+, but not in AT2-/- mice. In conclusion, this study demonstrates that the presence of functional AT2 receptors is necessary to observe the contribution of the vascular kinin-kallikrein system to flow-dependent dilation.
血管激肽释放酶-激肽系统通过激活与内皮一氧化氮(NO)释放偶联的缓激肽B2受体,在小鼠颈动脉中约三分之一的流量依赖性扩张中发挥作用。由于缓激肽/NO途径可能介导血管紧张素II AT2受体的某些作用,我们研究了AT2受体对激肽依赖性流量反应的可能贡献。在野生型动物(TK+/+)和组织激肽释放酶缺陷小鼠(TK-/-)的灌注动脉中评估了流速增加后外径的变化,其中已证实存在AT2受体表达。非选择性血管紧张素II受体拮抗剂沙拉新显著损害了TK+/+小鼠中流量诱导的扩张,而对TK-/-小鼠没有影响。在两组中,用氯沙坦或坎地沙坦阻断AT1受体均不影响对流量的反应。用PD123319抑制AT2受体显著降低了TK+/+小鼠中流量诱导的扩张,但对TK-/-小鼠没有显著影响。在TK+/+动脉中,将PD123319与缓激肽B2受体拮抗剂HOE-140联合使用对单独阻断AT2受体没有额外影响。与野生型同窝小鼠相比,AT2受体缺陷小鼠(AT2-/-)中流量依赖性扩张也受损。此外,HOE-140显著降低了AT2+/+小鼠对流量的反应,但对AT2-/-小鼠没有影响。总之,本研究表明,功能性AT2受体的存在对于观察血管激肽-激肽释放酶系统对流量依赖性扩张的贡献是必要的。