Lentz Linnea R, Valberg Stephanie J, Herold Lee V, Onan Gary W, Mickelson James R, Gallant Esther M
Department of Clinical and Population Sciences, University of Minnesota, St Paul, MN 55108, USA.
Am J Vet Res. 2002 Dec;63(12):1724-31. doi: 10.2460/ajvr.2002.63.1724.
To determine whether alterations in myoplasmic calcium regulation can be identified in muscle cell cultures (myotubes) and intact muscle fiber bundles derived from Thoroughbreds affected with recurrent exertional rhabdomyolysis (RER).
6 related Thoroughbreds with RER and 8 clinically normal (control) Thoroughbred or crossbred horses.
Myotube cell cultures were grown from satellite cells obtained from muscle biopsy specimens of RER-affected and control horses. Fura-2 fluorescence was used to measure resting myoplasmic calcium concentration as well as caffeine- and 4-chloro-m-cresol (4-CMC)-induced increases in myoplasmic calcium. In addition, intact intercostal muscle fiber bundles were prepared from both types of horses, and their sensitivities to caffeine- and 4-CMC-induced contractures were determined.
Myotubes of RER-affected and control horses had identical resting myoplasmic calcium concentrations. Myotubes from RER-affected horses had significantly higher myoplasmic calcium concentrations than myotubes from control horses following the addition of > or = 2mM caffeine; however, there was no difference in their response to 4-CMC (> or = 1 mM). Caffeine contracture thresholds for RER and control intact muscle cell bundles (2 vs 10mM, respectively) were significantly different, but 4-CMC contracture thresholds of muscle bundles from RER-affected and control horses (500 microM) did not differ.
An increase in caffeine sensitivity of muscle cells derived from a family of related RER-affected horses was detected in vitro by use of cell culture with calcium imaging and by use of fiber bundle contractility techniques. An alteration in muscle cell calcium regulation is a primary factor in the cause of this heritable myopathy.
确定在患有复发性运动性横纹肌溶解症（RER）的纯种马的肌肉细胞培养物（肌管）和完整肌纤维束中，是否能识别出肌浆钙调节的改变。
6匹患有RER的相关纯种马和8匹临床正常（对照）的纯种马或杂交马。
从受RER影响的马和对照马的肌肉活检标本中获取卫星细胞，培养肌管细胞。使用Fura-2荧光测量静息肌浆钙浓度以及咖啡因和4-氯间甲酚（4-CMC）诱导的肌浆钙增加。此外，从两种类型的马制备完整的肋间肌纤维束，并确定它们对咖啡因和4-CMC诱导的挛缩的敏感性。
受RER影响的马和对照马的肌管具有相同的静息肌浆钙浓度。添加≥2mM咖啡因后，受RER影响的马的肌管的肌浆钙浓度显著高于对照马的肌管；然而，它们对4-CMC（≥1mM）的反应没有差异。RER和对照完整肌细胞束的咖啡因挛缩阈值（分别为2和10mM）有显著差异，但受RER影响的马和对照马的肌肉束的4-CMC挛缩阈值（500 microM）没有差异。
通过使用钙成像细胞培养和纤维束收缩技术，在体外检测到来自一组相关受RER影响的马家族的肌肉细胞对咖啡因的敏感性增加。肌肉细胞钙调节的改变是这种遗传性肌病病因的主要因素。
