Departments of Physiology (G.D., Z.É.M., L.C., P.P.N., J.A.) and Biochemistry and Molecular Biology (J.A.M.), and Research Centre for Molecular Medicine (I.J.), Faculty of Medicine, and Department of Dental Physiology and Pharmacology, Faculty of Dentistry (P.P.N.), University of Debrecen, Debrecen, Hungary.
Departments of Physiology (G.D., Z.É.M., L.C., P.P.N., J.A.) and Biochemistry and Molecular Biology (J.A.M.), and Research Centre for Molecular Medicine (I.J.), Faculty of Medicine, and Department of Dental Physiology and Pharmacology, Faculty of Dentistry (P.P.N.), University of Debrecen, Debrecen, Hungary
Mol Pharmacol. 2019 Sep;96(3):401-407. doi: 10.1124/mol.119.116475. Epub 2019 Jul 23.
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 Ca 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, Mg was demonstrated to be the essential factor for dantrolene to inhibit Ca release in skinned muscle fibers. The aim of the present study was to confirm these results in Ca release and bilayer experiments, using SR vesicles and solubilized channels, respectively. Our Ca release experiments demonstrated that the effect of dantrolene and Mg was cooperative and that ATP enhanced the inhibiting effect of dantrolene. Namely, 10 M dantrolene reduced RyR channel open probability by ∼50% in the presence of 3 mM free Mg and 1 mM ATP, whereas channel activity further decreased to ∼20% of control when [ATP] was increased to 2 mM. Our data provide important complementary information that supports the direct, Mg-dependent mechanism of dantrolene's action and suggests that dantrolene also requires ATP to inhibit RyR.
丹曲林钠是一种肌浆网钙释放通道（RyR）抑制剂，用于治疗恶性高热综合征时肌肉紧张。尽管丹曲林钠能与 RyR 蛋白结合，但由于实验结果相互矛盾，其作用机制尚不清楚，主要是因为实验表明丹曲林钠能抑制完整纤维和肌浆网囊泡中的 Ca 释放，但不能抑制双层膜中的单个 RyR 通道电流。因此，人们认为 RyR 纯化过程中丢失了丹曲林钠作用的一个重要因素。最近的研究表明，Mg 是丹曲林钠抑制肌纤维去极化引起的 Ca 释放所必需的。本研究旨在通过肌浆网囊泡和可溶性通道的 Ca 释放实验和双层膜实验，分别确认这些结果。我们的 Ca 释放实验表明，丹曲林钠和 Mg 的作用具有协同性，ATP 增强了丹曲林钠的抑制作用。即在 3 mM 游离 Mg 和 1 mM ATP 存在的情况下，10 μM 丹曲林钠将 RyR 通道开放概率降低约 50%，而当 [ATP] 增加到 2 mM 时，通道活性进一步降低至对照的 20%左右。我们的数据提供了重要的补充信息，支持了丹曲林钠直接依赖 Mg 的作用机制，并表明丹曲林钠也需要 ATP 来抑制 RyR。
