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首页> 外文期刊>Artificial cells, blood substitutes, and biotechnology >Relative roles of heme-irons and globin-thiols in the genesis of acellular hemoglobin mediated vasoconstriction
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Relative roles of heme-irons and globin-thiols in the genesis of acellular hemoglobin mediated vasoconstriction

机译：血红素铁和球蛋白硫醇在无细胞血红蛋白介导的血管收缩中的相对作用

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In addition to heme-irons, reactive (β-globin thiols (βCys93s) of hemoglobin (Hb) also have been shown to interact with endogenous nitric oxide (NO) thereby contributing to vascular tone regulation. What relative roles do these NO binding sites contribute to the overall Hb-mediated vasoactivity? Several test Hbs with either or both the NO binding sites preliganded or blocked were prepared and tested in a rat thoracic aortic ring model. Hbs tested were: NEM-Hb (ferrous Hb with masked thiols), HbNO (ferrous Hb preliganded with NO), Hb+CN (ferric Hb liganded with CN-), NEM-HbNO and NEM-Hb+CN (Hbs with both heme-iron and cysteine sites preliganded or blocked). Typically, 0.2 μM control Hb significantly increased isometric tension in agonist stimulated vessel rings (58.1 ±7.0% over baseline). At comparable concentrations, NEM-Hb also caused a significant contraction (50.7±9.5%) while HbNO and Hb+CN did not (-5.5±6.0% and -3.7±4.6%, respectively). For these Hbs, masking thiols as well did not significantly alter respective vascular effects. Ferrous sperm whale myoglobin (Mb), which has no reactive thiol, elicited a significant contraction (55.1±13.2%) while metMb did not (-0.8±3.2%), suggesting the relative importance of heme-iron ligand and oxidation state in Hb vasoactivity. Additionally, ferrous or ferric equine heart cytochrome-C, a heme protein with no readily available heme-iron and cysteine binding sites, did not elicit notable contraction. Human Hb variants in which (βCys93s are deleted or substituted with non-cysteine residues did not reveal any documented significant hemodynamic abnormalities. These results indicate that reactive globin-thiols do not appear to play a prominent role relative to heme-irons in Hb-mediated vasoconstriction.
机译：除血红素铁外，血红蛋白（Hb）的反应性（β-球蛋白硫醇（βCys93s）也与内源性一氧化氮（NO）相互作用，从而有助于调节血管紧张度。这些NO结合位点起什么相对作用到总的Hb介导的血管活性？在大鼠胸主动脉环模型中制备并测试了一些带有一个或两个NO结合位点被预先配位或被封闭的测试Hb，测试的Hb为：NEM-Hb（带有掩蔽硫醇的亚铁Hb），HbNO （含Hb的亚铁Hb），Hb + CN（含CN-的三价铁Hb），NEM-HbNO和NEM-Hb + CN（具有血红素铁和半胱氨酸位点的Hbs被预先配位或封闭）。通​​常，> 0.2μM对照Hb显着增加激动剂刺激的血管环的等轴测张力（比基线高58.1±7.0％），在可比较的浓度下，NEM-Hb也会引起显着收缩（50.7±9.5％），而HbNO和Hb + CN则不会（-5.5±6.0） ％和-3.7±4.6％）。对于这些Hb，n的掩蔽硫醇它会显着改变各自的血管作用。无反应性硫醇的抹香鲸肌红蛋白（Mb）引起显着收缩（55.1±13.2％），而metMb无收缩（-0.8±3.2％），表明血红素铁配体和Hb中氧化态的相对重要性血管活性。另外，亚铁或铁马心脏细胞色素-C，一种没有随时可用的血红素铁和半胱氨酸结合位点的血红素蛋白，未引起明显的收缩。人类Hb变异体（βCys93s被缺失或被非半胱氨酸残基取代）未显示任何已记录的明显血流动力学异常。这些结果表明，在Hb介导的情况下，反应性球蛋白硫醇相对于血红素铁似乎没有发挥重要作用。血管收缩。

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