Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Victoria, Australia.
Liver Unit, Austin Health, Heidelberg, Victoria, Australia.
Hepatol Commun. 2022 Sep;6(9):2523-2537. doi: 10.1002/hep4.1987. Epub 2022 May 20.
Splanchnic vasodilatation contributes to the development and aggravation of portal hypertension (PHT). We previously demonstrated that in cirrhosis, angiotensin- mediates splanchnic vasodilatation through the Mas receptor (MasR). In this study, we investigated whether the recently characterized second receptor for angiotensin-(1-7), Mas-related G protein-coupled receptor type D (MrgD), contributes to splanchnic vasodilatation in cirrhotic and noncirrhotic PHT. Splanchnic vascular hemodynamic and portal pressure were determined in two rat models of cirrhotic PHT and a rat model with noncirrhotic PHT, treated with either MrgD blocker D-Pro -Ang-(1-7) (D-Pro) or MasR blocker A779. Gene and protein expression of MrgD and MasR were measured in splanchnic vessels and livers of cirrhotic and healthy rats and in patients with cirrhosis and healthy subjects. Mesenteric resistance vessels isolated from cirrhotic rats were used in myographs to study their vasodilatory properties. MrgD was up-regulated in cirrhotic splanchnic vessels but not in the liver. In cirrhotic rats, treatment with D-Pro but not A779 completely restored splanchnic vascular resistance to a healthy level, resulting in a 33% reduction in portal pressure. Mesenteric vessels pretreated with D-Pro but not with A779 failed to relax in response to acetylcholine. There was no splanchnic vascular MrgD or MasR up-regulation in noncirrhotic PHT; thus, receptor blockers had no effect on splanchnic hemodynamics. Conclusion: MrgD plays a major role in the development of cirrhotic PHT and is a promising target for the development of novel therapies to treat PHT in cirrhosis. Moreover, neither MrgD nor MasR contributes to noncirrhotic PHT.
内脏血管舒张导致门静脉高压症(PHT)的发展和恶化。我们之前证明,在肝硬化中,血管紧张素通过 Mas 受体(MasR)介导内脏血管舒张。在这项研究中,我们研究了最近被描述的血管紧张素-(1-7)的第二个受体,Mas 相关 G 蛋白偶联受体 D 型(MrgD),是否有助于肝硬化和非肝硬化 PHT 中的内脏血管舒张。我们在两个肝硬化 PHT 大鼠模型和一个非肝硬化 PHT 大鼠模型中测定了内脏血管血流动力学和门静脉压力,并用 MrgD 阻断剂 D-Pro -Ang-(1-7)(D-Pro)或 MasR 阻断剂 A779 进行处理。我们在肝硬化和健康大鼠以及肝硬化患者的内脏血管和肝脏中测量了 MrgD 和 MasR 的基因和蛋白表达。我们使用来自肝硬化大鼠的肠系膜阻力血管在肌动描记器中研究它们的血管舒张特性。MrgD 在肝硬化内脏血管中上调,但在肝脏中没有上调。在肝硬化大鼠中,用 D-Pro 处理而不是 A779 完全将内脏血管阻力恢复到健康水平,导致门静脉压力降低 33%。用 D-Pro 预处理但不用 A779 预处理的肠系膜血管对乙酰胆碱无反应性舒张。非肝硬化 PHT 中没有内脏血管 MrgD 或 MasR 上调;因此,受体阻断剂对内脏血流动力学没有影响。结论:MrgD 在肝硬化 PHT 的发展中起主要作用,是开发治疗肝硬化 PHT 新疗法的有希望的靶点。此外,MrgD 和 MasR 都不参与非肝硬化 PHT。
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