Dantrolene Requires Mg2+ and ATP To Inhibit the Ryanodine Receptor
Dantrolene Requires Mg2+ and ATP To Inhibit the Ryanodine Receptor
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DOI：
10.1124/mol.119.116475
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发表时间：
2019-09-01
影响因子：
3.6
通讯作者：
Almassy, Janos
中科院分区：
文献类型：
--
作者：
Diszhazi, Gyula;Magyar, Zsuzsanna Edua;Almassy, Janos
丹曲林是一种兰尼定受体(RyR)抑制剂，用于恶性高热综合征的肌肉松弛。虽然丹曲林与RyR蛋白结合，但其作用机制尚不清楚，主要是因为有争议的结果表明，丹曲烯抑制完整纤维和肌浆网(SR)小泡的钙释放，但不能抑制双层上的单个RyR通道电流。因此，在RyR的纯化过程中，丹曲林的作用失去了一个重要的因素。最近发现，镁离子是丹曲林抑制皮肤肌纤维钙释放的重要因素。本研究的目的是在钙释放和双层实验中证实这些结果，分别使用SR囊泡和增溶通道。Ca~(2+)释放实验表明，丹曲林和镁离子具有协同作用，而ATP则增强了丹曲烯的抑制作用。也就是说，在3 mM游离镁离子和1 mMATP存在下，10 mU丹曲林使RyR通道开放概率降低了50%，而当[ATP]增加到2 mM时，通道活动进一步降低到与对照相似的20%。我们的数据提供了重要的补充信息，支持丹曲林作用的直接、依赖于镁的机制，并表明丹曲林也需要ATP来抑制RyR。
Dantrolene is a ryanodine receptor (RyR) inhibitor, which is used to relax muscles in malignant hyperthermia syndrome. Although dantrolene binds to the RyR protein, its mechanism of action is unknown, mainly because of the controversial results showing that dantrolene inhibited Ca2+ release from intact fibers and sarcoplasmic reticulum (SR) vesicles, but failed to inhibit single RyR channel currents in bilayers. Accordingly, it was concluded that an important factor for dantrolene's action was lost during the purification procedure of RyR. Recently, Mg2+ was demonstrated to be the essential factor for dantrolene to inhibit Ca2+ release in skinned muscle fibers. The aim of the present study was confirm these results in Ca2+ release and bilayer experiments, using SR vesicles and solubilized channels, respectively. Our Ca2+ release experiments demonstrated that the effect of dantrolene and Mg2+ was cooperative and that ATP enhanced the inhibiting effect of dantrolene. Namely, 10 mu M dantrolene reduced RyR channel open probability by similar to 50% in the presence of 3 mM free Mg2+ and 1 mMATP, whereas channel activity further decreased to similar to 20% of control when [ATP] was increased to 2 mM. Our data provide important complementary information that supports the direct, Mg2+-dependent mechanism of dantrolene's action and suggests that dantrolene also requires ATP to inhibit RyR.