Beech J, Lindborg S, Fletcher J E, Lizzo F, Tripolitis L, Braund K
Department of Clinical Studies, University of Pennsylvania, School of Veterinary Medicine, Kennett Square 19348.
Res Vet Sci. 1993 Jan;54(1):110-7. doi: 10.1016/0034-5288(93)90019-c.
Muscle from horses with intermittent exercise associated rhabdomyolysis was examined to determine if calcium regulation was abnormal. In vitro studies on semimembranosus muscle fibre bundles showed the time to 50 per cent relaxation of caffeine-induced contractures was shorter and the electrically elicited twitch longer in horses with exercise associated rhabdomyolysis. Substitution of strontium for calcium eliminated the difference in caffeine contracture between the normal and rhabdomyolysis horses. The threshold of calcium-induced calcium release was lower than normal in terminal cisternae-containing fractions of muscle from horses with rhabdomyolysis. Thoroughbreds with rhabdomyolysis had a shorter time to peak twitch tension than standardbreds, and normal thoroughbreds had a shorter caffeine contracture than normal standardbreds. There was no difference in fibre typing between breeds or groups. Either no histological changes or low grade to moderate degenerative myopathy was seen in muscle from horses with rhabdomyolysis. These results suggest horses with intermittent exercise associated rhabdomyolysis have abnormal calcium regulation.
对患有间歇性运动相关性横纹肌溶解症的马匹的肌肉进行检查，以确定钙调节是否异常。对半膜肌纤维束的体外研究表明，患有运动相关性横纹肌溶解症的马匹，咖啡因诱导的挛缩50%松弛时间更短，电诱发抽搐时间更长。用锶替代钙消除了正常马匹和横纹肌溶解症马匹之间咖啡因挛缩的差异。患有横纹肌溶解症的马匹肌肉中含终末池的部分，钙诱导钙释放的阈值低于正常水平。患有横纹肌溶解症的纯种马达到抽搐张力峰值的时间比标准赛马短，正常纯种马的咖啡因挛缩时间比正常标准赛马短。不同品种或组之间的纤维类型没有差异。患有横纹肌溶解症的马匹的肌肉要么没有组织学变化，要么有轻度至中度的退行性肌病。这些结果表明，患有间歇性运动相关性横纹肌溶解症的马匹存在钙调节异常。
