Effects of mercury on myosin ATPase in the ventricular myocardium of the rat
Effects of mercury on myosin ATPase in the ventricular myocardium of the rat
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DOI：
10.1016/s1532-0456(03)00110-8
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发表时间：
2003-07-01
影响因子：
3.9
通讯作者：
Vassallo, DV
中科院分区：
文献类型：
--
作者：
Moreira, CM;Oliveira, EM;Vassallo, DV
汞可减少离体大鼠乳头肌的抽搐和强直力发展，并可能对收缩机械产生毒性作用。在此基础上，研究了HgCl2对左心室心肌肌球蛋白atp酶活性的影响。取大鼠左心室肌球蛋白三磷酸腺苷酶活性测定样品。HgCl2浓度的增加使肌球蛋白atp酶的活性呈剂量依赖性降低。即使在非常小的浓度（50 nM的HgCl2）下也观察到这种减少。这种作用依赖于肌球蛋白分子中SH基团的存在，因为DTT和谷胱甘肽保护肌球蛋白atp酶免受汞的毒性作用；500nm的DTT或500nm的谷胱甘肽可恢复活性。结果还表明，汞作为一种非竞争性抑制剂，其K-i为200 nM HgCl2。我们的研究结果表明，在非常低的剂量下，汞通过非竞争性机制降低肌球蛋白atp酶的活性，而不抑制力。DTT和谷胱甘肽对汞的作用具有有效的保护作用，提示SH基团可能是金属对肌球蛋白分子的作用位点。(C) 2003 Elsevier Inc.版权所有。
Mercury reduces twitch and tetanic force development in isolated rat papillary muscles, and a putative toxic effect on the contractile machinery has been suggested. Based on that, the actions of HgCl2 on the myosin ATPase activity of the left ventricular myocardium were investigated. Samples for assay of myosin ATPase activity were obtained from rats' left ventricles. Increasing concentrations of HgCl2 reduced dose-dependently the activity of the myosin ATPase. This reduction was observed even at very small concentrations, 50 nM HgCl2. This effect was dependent on the presence of SH groups in the myosin molecule since DTT and glutathione protected the myosin ATPase against toxic effects of mercury; full activity being restored by using 500 nM DTT or 500 nM glutathione. Results also suggested that the metal acts as an uncompetitive inhibitor with a K-i of 200 nM HgCl2 Our results suggest that mercury reduces the activity of the myosin ATPase by an uncompetitive mechanism at a very low dose that does not depress force. DTT and glutathione are effective for protection against the actions of mercury suggesting that SH groups might be the sites of action of the metal on the myosin molecule. (C) 2003 Elsevier Inc. All rights reserved.