Clinical concentrations of doxorubicin inhibit activity of myocardial membrane-associated, calcium-independent phospholipase A(2).
Clinical concentrations of doxorubicin inhibit activity of myocardial membrane-associated, calcium-independent phospholipase A(2).
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发表时间：
2001-05
期刊：
影响因子：
11.2
通讯作者：
J. McHowat;L. Swift;A. Arutunyan;N. Sarvazyan
中科院分区：
文献类型：
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作者：
J. McHowat;L. Swift;A. Arutunyan;N. Sarvazyan
抗癌抗生素阿霉素的使用仍然受到其累积剂量相关心脏毒性的限制。我们的研究报告了临床相关浓度的药物对心肌细胞内钙非依赖性磷脂酶A（2）（iPLA（2））活性的抑制作用。该效应首先在体外使用新鲜分离的大鼠和兔心肌细胞的悬浮液显示。向这些细胞中加入0.1-10 μ M阿霉素导致总iPLA的浓度和时间依赖性抑制（2），在存在或不存在钙的情况下使用（16：0，[（3）H]18：1）血浆胆碱和磷脂酰胆碱底物进行测量。亚细胞分级分离为胞质和膜组分，显示药物选择性抑制膜相关的iPLA（2）活性，而不改变胞质酶的活性。阿霉素处理用[H（3）]花生四烯酸预标记的细胞导致基线花生四烯酸释放水平下降，证实了iPLA（2）抑制作用。在心肌细胞悬液中，还原剂阻断了PLA（2）的抑制作用，这表明阿霉素的作用是由敏感的半胱氨酸氧化介导的。在体内实验中，成年大鼠静脉注射4 mg/kg剂量的多柔比星，证实了体外研究结果，显示在治疗动物的心脏组织中，膜相关的Ca（2+）非依赖性iPLA（2）活性降低了2倍。所观察到的现象对肌细胞信号级联和膜重塑具有重要意义。
Use of the anticancer antibiotic doxorubicin continues to be limited by its cumulative dose-related cardiotoxicity. Our study reports inhibition of myocardial intracellular calcium-independent phospholipase A(2) (iPLA(2)) activity by clinically relevant concentrations of the drug. The effect was first shown in vitro using suspensions of freshly isolated rat and rabbit cardiomyocytes. Addition of 0.1-10 microM doxorubicin to these cells led to a concentration- and time-dependent inhibition of total iPLA(2), as measured using (16:0, [(3)H]18:1) plasmenylcholine and phosphatidylcholine substrates in the presence or absence of calcium. Subcellular fractionation into cytosolic and membrane fraction revealed that the drug selectively inhibits membrane-associated iPLA(2) activity, without altering activity of the cytosolic enzyme. Doxorubicin treatment of cells prelabeled with [H(3)]arachidonic acid led to a depression of baseline arachidonic acid release levels, corroborating iPLA(2) inhibition. Reducing agents blocked PLA(2) inhibition in cardiomyocyte suspensions, suggesting that the doxorubicin effect is mediated by oxidation of susceptible cysteines. In vivo experiments, in which adults rats were i.v. injected with a bolus dose of 4 mg/kg doxorubicin, confirmed in vitro findings, revealing a 2-fold decrease in membrane-associated Ca(2+)-independent iPLA(2) activity in the heart tissue of treated animals. The observed phenomenon has important implications for myocyte signaling cascades and membrane remodeling.