Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, MA, USA; Department of Molecular Biosciences, School of Veterinary Medicine, University of California at Davis, Davis, CA, USA.
Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, UK.
Br J Anaesth. 2018 Oct;121(4):953-961. doi: 10.1016/j.bja.2018.07.008. Epub 2018 Aug 10.
The human p.G2434R variant of the RYR1 gene is most frequently associated with malignant hyperthermia (MH) in the UK. We report the phenotype of a knock-in mouse that expresses the RYR1 variant p.G2435R, which is isogenetic with the human variant.
We observed the general phenotype; determined the sensitivity of myotubes to caffeine-, KCl, and halothane-induced Ca release; determined the in vivo response to halothane or increased ambient temperature; and determined the in vivo myoplasmic intracellular Ca concentration in skeletal muscle before and during exposure to volatile anaesthetics.
RYR1 pG2435R/MH normal (MHS-Heterozygous[Het]) or RYR1 pG2435R/pG2435R (MHS-Homozygous[Hom]) mice were fully viable under typical rearing conditions, although some male MHS-Hom mice died spontaneously. The normalised half-maximal effective concentration (95% confidence interval) for intracellular Ca release in myotubes in response to KCl [MH normal, MHN, 21.4 (19.8-23.1) mM; MHS-Het 16.2 (15.2-17.2) mM; MHS-Hom 11.2 (10.2-12.2) mM] and caffeine (MHN, 5.7 (5-6.3) mM; MHS-Het 4.5 (3.9-5.0) mM; MHS-Hom 1.77 (1.5-2.1) mM] exhibited a gene dose-dependent decrease, and there was a gene dose-dependent increase in halothane sensitivity. Intact animals show a gene dose-dependent susceptibility to MH with volatile anaesthetics or to heat stroke. RYR1 p.G2435R mice had elevated skeletal muscle intracellular resting [Ca], (values are expressed as mean (SD)) (MHN 123 (3) nM; MHS-Het 156 (16) nM; MHS-Hom 265 (32) nM; P<0.001) and [Na] (MHN 8 (0.1) mM; MHS-Het 10 (1) mM; MHS-Hom 14 (0.7) mM; P<0.001) that was further increased by exposure to volatile anaesthetics.
RYR1 pG2435R mice demonstrated gene dose-dependent in vitro and in vivo responses to pharmacological and environmental stressors that parallel those seen in patients with the human RYR1 variant p.G2434R.
RYR1 基因的人类 p.G2434R 变体与英国的恶性高热（MH）最常相关。我们报告了表达 RYR1 变体 p.G2435R 的基因敲入小鼠的表型，该变体与人类变体同系。
我们观察了一般表型；确定肌管对咖啡因、KCl 和氟烷诱导的 Ca 释放的敏感性；确定氟烷或环境温度升高时的体内反应；并确定挥发性麻醉剂暴露前后骨骼肌中的体内肌浆细胞内 Ca 浓度。
在典型的饲养条件下，RYR1 pG2435R/MH 正常（MHS-杂合子[Het]）或 RYR1 pG2435R/pG2435R（MHS-纯合子[Hom]）小鼠完全具有活力，尽管一些雄性 MHS-Hom 小鼠自发死亡。肌管对 KCl [MH 正常，MHN，21.4（19.8-23.1）mM；MHS-Het 16.2（15.2-17.2）mM；MHS-Hom 11.2（10.2-12.2）mM]和咖啡因（MHN，5.7（5-6.3）mM；MHS-Het 4.5（3.9-5.0）mM；MHS-Hom 1.77（1.5-2.1）mM）的细胞内 Ca 释放的半最大有效浓度（95%置信区间）呈基因剂量依赖性降低，氟烷敏感性呈基因剂量依赖性增加。完整动物对挥发性麻醉剂或中暑表现出基因剂量依赖性对 MH 的易感性。RYR1 p.G2435R 小鼠对挥发性麻醉剂或中暑的骨骼肌细胞内静息 [Ca]（以平均值（SD）表示）（MHN 123（3）nM；MHS-Het 156（16）nM；MHS-Hom 265（32）nM；P<0.001）和 [Na]（MHN 8（0.1）mM；MHS-Het 10（1）mM；MHS-Hom 14（0.7）mM；P<0.001）升高，暴露于挥发性麻醉剂后进一步升高。
RYR1 p.G2435R 小鼠表现出与人类 RYR1 变体 p.G2434R 患者相似的基因剂量依赖性体外和体内对药理学和环境应激的反应。
