Hildebrand S V, Arpin D, Cardinet G
Department of Veterinary Surgery, School of Veterinary Medicine, University of California, Davis 95616.
J Am Vet Med Assoc. 1990 Apr 1;196(7):1077-83.
Biopsy specimens of the cutaneous omobrachialis muscle were obtained from 10 horses with a problem of myositis from mild exercise. One horse had been evaluated previously and malignant hyperthermia-like contractures developed in its muscle biopsy specimen during the contracture test. In this study, the halothane-caffeine contracture test and histologic and histochemical evaluations were performed on muscle biopsy specimens. In the contracture test, no muscle biopsy specimen developed contracture in the presence of 2 or 4% halothane alone. The mean (+/- SEM) caffeine-specific concentration in the presence of halothane was 5.23 +/- 0.5 mM for 2% halothane, and 4.46 +/- 0.6 mM for 4% halothane. The caffeine-specific concentration values were not significantly different. Contracture response for any muscle specimen did not resemble contracture associated with malignant hyperthermia. The cutaneous omobrachialis muscle was composed of type-II fibers, with type-I fibers seldom seen. For 9 of the 10 horses, overall fiber morphology was normal; 1 horse had necrotic fibers. Of the 10 muscle specimens, 9 had fibers that had positive reaction for alkaline phosphatase activity; 3 muscle specimens contained ringed myofibers. Three horses of this study were administered general anesthesia; 2 were research horses, anesthetized with halothane and succinylcholine, and 1 was a clinical case given halothane anesthesia plus a non-depolarizing muscle relaxant. One research horse developed a malignant hyperthermia-like reaction to anesthesia, with severe rhabdomyolysis evident after anesthesia, and an episode of muscle cramping in its stall 2 days after anesthesia. The other 2 horses had unremarkable postanesthetic periods.
从10匹因轻度运动出现肌炎问题的马身上获取了臂三头肌皮肤活检标本。其中一匹马之前已接受评估，其肌肉活检标本在挛缩试验中出现了恶性高热样挛缩。在本研究中，对肌肉活检标本进行了氟烷 - 咖啡因挛缩试验以及组织学和组织化学评估。在挛缩试验中，单独使用2%或4%氟烷时，没有肌肉活检标本出现挛缩。在氟烷存在的情况下，2%氟烷时咖啡因特异性浓度的平均值（±标准误）为5.23±0.5 mM，4%氟烷时为4.46±0.6 mM。咖啡因特异性浓度值无显著差异。任何肌肉标本的挛缩反应都与恶性高热相关的挛缩不同。臂三头肌皮肤肌由II型纤维组成，很少见到I型纤维。10匹马中有9匹的总体纤维形态正常；1匹马有坏死纤维。10个肌肉标本中有9个纤维对碱性磷酸酶活性呈阳性反应；3个肌肉标本含有环状肌纤维。本研究中的3匹马接受了全身麻醉；2匹是研究用马，用氟烷和琥珀酰胆碱麻醉，1匹是临床病例，接受氟烷麻醉加非去极化肌肉松弛剂。一匹研究用马对麻醉出现了恶性高热样反应，麻醉后明显出现严重横纹肌溶解，麻醉后2天在厩舍中出现一次肌肉痉挛。另外2匹马麻醉后情况正常。
