Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy.
Department of Pharmacy, University of Pisa, Pisa, Italy.
Br J Pharmacol. 2020 Feb;177(4):810-823. doi: 10.1111/bph.14700. Epub 2019 May 3.
Human malignant hyperthermia (MH) syndrome is induced by volatile anaesthetics and involves increased levels of cystathionine β-synthase (CBS)-derived H S within skeletal muscle. This increase contributes to skeletal muscle hypercontractility. K 7 channels, expressed in skeletal muscle, may be a molecular target for H S. Here, we have investigated the role of K 7 channels in MH.
Skeletal muscle biopsies were obtained from MH-susceptible (MHS) and MH-negative (MHN) patients. Immunohistochemistry, RT-PCR, Western blot, and in vitro contracture test (IVCT) were carried out. Development and characterization of primary human skeletal muscle cells (PHSKMC) and evaluation of cell membrane potential were also performed. The persulfidation state of K 7 channels and polysulfide levels were measured.
K 7 channels were similarly expressed in MHN and MHS biopsies. The IVCT revealed an anomalous contractility of MHS biopsies following exposure to the K 7 channel opener retigabine. Incubation of negative biopsies with NaHS, prior to retigabine addition, led to an MHS-like positive response. MHS-derived PHSKMC challenged with retigabine showed a paradoxical depolarizing effect, compared with the canonical hyperpolarizing effect. CBS expression and activity were increased in MHS biopsies, resulting in a major polysulfide bioavailability. Persulfidation of K 7.4 channels was significantly higher in MHS than in MHN biopsies.
In skeletal muscle of MHS patients, CBS-derived H S induced persulfidation of K 7 channels. This post-translational modification switches the hyperpolarizing activity into depolarizing. This mechanism can contribute to the pathological skeletal muscle hypercontractility typical of MH syndrome.
This article is part of a themed section on Hydrogen Sulfide in Biology & Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.4/issuetoc.
人类恶性高热（MH）综合征是由挥发性麻醉剂诱导的，涉及骨骼肌中胱硫醚β-合酶（CBS）衍生的 H₂S 水平升高。这种增加导致骨骼肌高收缩性。在骨骼肌中表达的 K₇ 通道可能是 H₂S 的分子靶标。在这里，我们研究了 K₇ 通道在 MH 中的作用。
从 MH 易感（MHS）和 MH 阴性（MHN）患者中获得骨骼肌活检。进行免疫组织化学、RT-PCR、Western blot 和体外收缩试验（IVCT）。还进行了原代人骨骼肌细胞（PHSKMC）的开发和表征以及细胞膜电位的评估。测量 K₇ 通道的过硫化状态和多硫化物水平。
在 MHN 和 MHS 活检中，K₇ 通道的表达相似。IVCT 显示，在暴露于 K₇ 通道开放剂瑞替加滨后，MHS 活检出现异常收缩性。在加入瑞替加滨之前，用 NaHS 孵育阴性活检会导致类似于 MHS 的阳性反应。与经典的超极化作用相比，用瑞替加滨挑战的 MHS 衍生的 PHSKMC 显示出矛盾的去极化作用。在 MHS 活检中，CBS 表达和活性增加，导致主要的多硫化物生物利用度增加。与 MHN 活检相比，MHS 活检中 K 7.4 通道的过硫化程度明显更高。
在 MHS 患者的骨骼肌中，CBS 衍生的 H₂S 诱导 K 7 通道的过硫化。这种翻译后修饰将超极化活性转变为去极化。这种机制可能有助于 MH 综合征典型的病理性骨骼肌高收缩性。
本文是关于氢硫化物在生物学和医学中的主题部分的一部分。要查看该部分中的其他文章，请访问 http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.4/issuetoc.
