β-blockade abolishes the augmented cardiac tPA release induced by transactivation of heterodimerised bradykinin receptor-2 and β2-adrenergic receptor in vivo
β-blockade abolishes the augmented cardiac tPA release induced by transactivation of heterodimerised bradykinin receptor-2 and β2-adrenergic receptor in vivo
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DOI：
10.1160/th14-01-0059
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发表时间：
2014-11-01
影响因子：
6.7
通讯作者：
Lyberg, Torstein
中科院分区：
文献类型：
--
作者：
Aspelin, Trude;Eriksen, Morten;Lyberg, Torstein
缓激肽(BK)受体-2(B2R)和β(2)-肾上腺素能受体(β(2)AR)在体外形成异二聚体。然而，B2R-β(2)AR异源二聚体的功能效应的体内证据尚不清楚。BK和肾上腺素能刺激都是tPA释放的已知诱导者。我们的目标是证明B2R-β(2)AR异源二聚体在心肌中的存在，并确定其对体内心脏释放tPA的功能影响。我们进一步研究了非选择性β-受体阻滞剂对这种受体相互作用的影响。为了研究B2R-β(2)AR异构化(即BK反式激活β(2)AR)在体内的功能效应，我们在接受BK输注的正常猪身上诱导了一系列的心脏交感神经(SS)电刺激。SS和BK单独引起心脏tPA释放增加。重要的是，尽管B2R脱敏，但同时注射BK和SS(BK+SS)的特点是，与单独使用SS相比，tPA释放增加2.3+/-0.3倍。当β-受体阻滞剂(心得安)先于BK+SS时，tPA的释放被抑制。免疫沉淀法和非还原凝胶实验证实，在BK刺激和非刺激的左室心肌中存在一种持久的B2R-β(2)AR异二聚体。综上所述，这些结果强烈表明BK反式激活β(2)AR导致增强的β(2)AR介导的tPA释放。重要的是，非选择性P-阻滞剂在体内既抑制了SS诱导的tPA释放，也抑制了B2R-β(2)AR异源二聚的功能效应，这可能具有重要的临床意义。
Bradykinin.(BK) receptor-2 (B2R) and beta(2)-adrenergic receptor (beta(2)AR) have been shown to form heterodimers in vitro. However, in vivo proofs of the functional effects of B2R-beta(2)AR heterodimerisation are missing. Both BK and adrenergic stimulation are known inducers of tPA release. Our goal was to demonstrate the existence of B2R-beta(2)AR heterodimerisation in myocardium and to define its functional effect on cardiac release of tPA in vivo. We further investigated the effects of a non-selective beta-blocker on this receptor interplay. To investigate functional effects of B2R-beta(2)AR heterodimerisation (i. e. BK transactivation of beta(2)AR) in vivo, we induced serial electrical stimulation of cardiac sympathetic nerves (SS) in normal pigs that underwent concomitant BK infusion. Both SS and BK alone induced increases in cardiac tPA release. Importantly, despite B2R desensitisation, simultaneous BK infusion and SS (BK+SS) was characterised by 2.3 +/- 0.3-fold enhanced tPA release compared to SS alone. When beta-blockade (propranolol) was introduced prior to BK+SS, tPA release was inhibited. A persistent B2R-beta(2)AR heterodimer was confirmed in BK-stimulated and non-stimulated left ventricular myocardium by immunoprecipitation studies and under non-reducing gel conditions. All together, these results strongly suggest BK transactivation of beta(2)AR leading to enhanced beta(2)AR-mediated release of tPA. Importantly, non-selective P-blockade inhibits both SS-induced release of tPA and the functional effects of B2R-beta(2)AR heterodimerisation in vivo, which may have important clinical implications.