Oxidation of myofilament protein sulfhydryl groups reduces the contractile force and its Ca2+ sensitivity in human cardiomyocytes
Oxidation of myofilament protein sulfhydryl groups reduces the contractile force and its Ca2+ sensitivity in human cardiomyocytes
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DOI：
10.1089/ars.2007.2014
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发表时间：
2008-07-01
影响因子：
6.6
通讯作者：
Papp, Zoltan
中科院分区：
文献类型：
--
作者：
Hertelendi, Zita;Toth, Attila;Papp, Zoltan
本研究旨在表征人心肌中蛋白质巯基（SH）组氧化与Ca2+激活力产生之间的关系。将供体心脏的trion -通透性左心室心肌细胞体外暴露于氧化（2,2'-二硫代二吡啶，DTDP）剂中，监测其等长力的变化、Ca2+敏感性、饱和状态下力再开发的过桥敏感速率常数[Ca2+] （k(tr,max)）和蛋白SH氧化。DTDP （0.1 ~ 10 mM, 2 min）对心肌蛋白有不同浓度依赖性的氧化作用，Ca2+激活力降低（EC50,SH = 0.17 +/- 0.02 mM, EC50，力= 2.46 +/- 0.22 mM，平均+/- SEM）。2.5 mM DTDP的应用降低了最大Ca2+激活力（64%），其Ca2+敏感性（δ pCa(50) = 0.22 +/- 0.02）和Ca2+-力关系的陡峭度（nHill，从2.01 +/- 0.08到1.76 +/- 0.08）。这些变化与蛋白质的游离SH含量降低（降至15%）和k（tr,max）降低（降至75%）相一致。SH特异性标记鉴定了DTDP浓度下肌球蛋白轻链1和肌动蛋白的SH氧化，收缩参数发生变化。我们的数据表明，选定的肌丝蛋白中的SH氧化通过损害人类心脏中肌动蛋白-肌球蛋白周期的Ca2+调节，降低了Ca2+活化力及其Ca2+敏感性。
This study sought to characterize the relation between the oxidation of protein sulfhydryl (SH) groups and Ca2+-activated force production in the human myocardium. Triton-permeabilized left ventricular cardiomyocytes from donor hearts were exposed to an oxidative (2,2'-dithiodipyridine, DTDP) agent in vitro, and the changes in isometric force, its Ca2+ sensitivity, the cross-bridge -sensitive rate constant of force redevelopment at saturating [Ca2+] (k(tr,max)), and protein SH oxidation were monitored. DTDP (0.1-10 mM for 2 min) oxidized the myocardial proteins and diminished the Ca2+-activated force with different concentration dependences (EC50,SH = 0.17 +/- 0.02 mM and EC50,force = 2.46 +/- 0.22 mM; mean +/- SEM). The application of 2.5 mM DTDP decreased the maximal Ca2+-activated force (to 64%), its Ca2+ sensitivity (Delta pCa(50) = 0.22 +/- 0.02), and the steepness of the Ca2+-force relation (nHill, from 2.01 +/- 0.08 to 1.76 +/- 0.08). These changes were paralleled by reductions in the free SH content of the proteins (to 15%) and in k(tr,max) (to 75%). SH-specific labeling identified SH oxidation of myosin light chain 1 and actin at DTDP concentrations at which the changes in the contractile parameters occurred. Our data suggest that SH oxidation in selected myofilament proteins diminishes the Ca2+-activated force and its Ca2+ sensitivity through an impaired Ca2+ regulation of the actin-myosin cycle in the human heart.