Radovits Tamás
Ruprecht-Karls Egyetem Szívsebészeti Klinika, Kísérleti Kutató Laboratórium Heidelberg Németország Semmelweis Egyetem, Altalános Orvostudományi Kar Kardiológiai Központ Budapest.
Orv Hetil. 2008 Dec 14;149(50):2377-85. doi: 10.1556/OH.2008.28502.
Overproduction of free radicals in ageing tissues induces nitro-oxidative stress, which has been implicated in the functional decline of the cardiovascular system at old age. Toxic oxidants like hydrogen peroxide or peroxynitrite damage proteins and DNA and activate several pathways causing tissue injury, including the poly(ADP-ribose) polymerase (PARP) pathway.
First, we tested whether the inhibition of PARP can improve endothelial dysfunction induced by hydrogen peroxide in an in vitro model of vascular oxidative stress. In turn, our main aim was to investigate the effects of acute PARP inhibition and catalytic peroxynitrite decomposition on ageing-associated cardiac and endothelial dysfunction.
In vascular reactivity measurements on isolated rat aortic rings, we investigated the endothelium-dependent and -independent vasorelaxation by using acetylcholine and sodium nitroprusside. Endothelial dysfunction was induced by hydrogen peroxide. In the treatment group, rings were preincubated with a PARP-inhibitor. In the in vivo rat model of ageing-associated cardiovascular dysfunction, young and ageing rats were treated with a single dose of PARP-inhibitor, or with the peroxynitrite decomposition catalyst FP15. Using a pressure-conductance catheter, left ventricular pressure-volume analysis was performed to study cardiac function. Endothelium-dependent and -independent relaxation of aortic rings were investigated. Immunohistochemical analysis was performed to study the changes on the cellular and tissue level.
In our in vitro model, hydrogen peroxide caused a dose-dependent impairment of endothelium-dependent vasorelaxation of aortic rings which was significantly improved by PARP-inhibition. Ageing rats showed a marked reduction of cardiac function and loss of endothelium-dependent relaxant responsiveness of aortic rings. Both acute PARP-inhibition and FP15-treatment improved cardiac performance and endothelial function. Immunohistochemistry confirmed enhanced nitro-oxidative stress and PARP-activation in ageing rats, which were reversed in the treatment groups.
Our results demonstrate the importance of endogenous peroxynitrite-overproduction and the activation of the PARP pathway in the age-related functional decline of the cardiovascular system. Catalytic peroxynitrite decomposition and PARP-inhibition may represent novel antioxidant therapeutic utilities to improve ageing-associated cardiovascular dysfunction.
衰老组织中自由基的过度产生会引发硝基氧化应激，这与老年时心血管系统的功能衰退有关。像过氧化氢或过氧亚硝酸根这样的有毒氧化剂会损害蛋白质和DNA，并激活多种导致组织损伤的途径，包括多聚（ADP-核糖）聚合酶（PARP）途径。
首先，我们在血管氧化应激的体外模型中测试了PARP抑制是否能改善过氧化氢诱导的内皮功能障碍。相应地，我们的主要目的是研究急性PARP抑制和催化过氧亚硝酸根分解对衰老相关的心脏和内皮功能障碍的影响。
在对分离的大鼠主动脉环进行血管反应性测量时，我们使用乙酰胆碱和硝普钠研究内皮依赖性和非内皮依赖性血管舒张。过氧化氢诱导内皮功能障碍。在治疗组中，主动脉环预先用PARP抑制剂孵育。在衰老相关心血管功能障碍的体内大鼠模型中，年轻和衰老大鼠用单剂量的PARP抑制剂或过氧亚硝酸根分解催化剂FP15进行治疗。使用压力-电导导管进行左心室压力-容积分析以研究心脏功能。研究主动脉环的内皮依赖性和非内皮依赖性舒张。进行免疫组织化学分析以研究细胞和组织水平的变化。
在我们的体外模型中，过氧化氢导致主动脉环内皮依赖性血管舒张呈剂量依赖性受损，而PARP抑制可显著改善这种情况。衰老大鼠表现出心脏功能明显降低以及主动脉环内皮依赖性舒张反应丧失。急性PARP抑制和FP15治疗均可改善心脏性能和内皮功能。免疫组织化学证实衰老大鼠中硝基氧化应激增强和PARP激活，而在治疗组中这些情况得到逆转。
我们的结果证明了内源性过氧亚硝酸根过度产生和PARP途径激活在心血管系统与年龄相关的功能衰退中的重要性。催化过氧亚硝酸根分解和PARP抑制可能代表改善衰老相关心血管功能障碍的新型抗氧化治疗手段。
