Kobayashi M, Mukaida K, Migita T, Hamada H, Kawamoto M, Yuge O
Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima, Japan.
Anaesth Intensive Care. 2011 Mar;39(2):252-61. doi: 10.1177/0310057X1103900216.
Malignant hyperthermia is a life-threatening condition caused by autosomal dominant mutations in the ryanodine receptor type 1 gene. Identifying patients predisposed to malignant hyperthermia is done through the Ca-induced Ca release test in Japan. We examined the intracellular calcium concentration in human cultured muscle cells and compared the sensitivity of myotubes to ryanodine receptor type 1 activators based on the Ca-induced Ca release rate. We assessed the utility of this method as an identifying test for predisposition to malignant hyperthermia. Muscle specimens were obtained from 34 individuals undergoing the Ca-induced Ca release test. We cultured myotubes from residual material and monitored changes in intracellular calcium concentration after exposure to the ryanodine receptor type 1 activators caffeine, halothane and 4-chloro-m-cresol by measuring fura-2 fluorescence. We determined the half maximal effective concentrations (EC50) for the test compounds in each myotube and calculated cut-off points using receiver operating characteristic curves. Seventeen patients each were classified into the accelerated and non-accelerated groups based on their Ca-induced Ca release rate. The EC50 values for caffeine, halothane and 4-chloro-m-cresol of the accelerated group were significant lower than those of the non-accelerated group (P < 0.001, P < 0.001 and P < 0.001, respectively). The calculated cut-off points of EC50 values for caffeine, halothane and 4-CmC were 3.62 mM, 2.28 mM and 197 microM, respectively. An increased sensitivity to ryanodine receptor type 1 activators was seen in myotubes in the accelerated group. This functional test on human cultured myotubes indicates that the alteration of their intracellular Ca2+ homeostasis may identify the predisposition to malignant hyperthermia.
恶性高热是一种由1型兰尼碱受体基因的常染色体显性突变引起的危及生命的病症。在日本，通过钙诱导钙释放试验来识别易患恶性高热的患者。我们检测了人培养肌肉细胞中的细胞内钙浓度，并根据钙诱导钙释放率比较了肌管对1型兰尼碱受体激活剂的敏感性。我们评估了该方法作为恶性高热易感性识别试验的效用。从34名接受钙诱导钙释放试验的个体中获取肌肉标本。我们从剩余材料中培养肌管，并通过测量fura-2荧光监测暴露于1型兰尼碱受体激活剂咖啡因、氟烷和4-氯间甲酚后细胞内钙浓度的变化。我们确定了每种肌管中试验化合物的半数最大有效浓度（EC50），并使用受试者工作特征曲线计算截断点。根据钙诱导钙释放率，17名患者分别被分为加速组和非加速组。加速组中咖啡因、氟烷和4-氯间甲酚的EC50值显著低于非加速组（分别为P < 0.001、P < 0.001和P < 0.001）。咖啡因、氟烷和4-CmC的EC50值计算出的截断点分别为3.62 mM、2.28 mM和197 microM。加速组的肌管对兰尼碱受体1型激活剂的敏感性增加。对人培养肌管的这种功能测试表明，其细胞内Ca2+稳态的改变可能识别出恶性高热的易感性。
