Hibernation effects on muscle morphological characteristics and fiber type composition in dauria ground squirrels (Spermophilus dauricus
首发时间:2011-01-19
Abstract:Aim: We studied effects of hibernation on extensor digitorum longus (EDL) weight, fiber cross-sectional area (CSA), fiber type distribution, and myosin ATPase activity in dauria ground squirrels (Spermophilus dauricus). Methods: Muscle mass, fiber CSA (video analysis), fiber type, and myosin ATPase activity (Ca2+-ATPase) were measured before and after 1 and 2 months of hibernation, and 2-4 days after arousal in different groups of ground squirrels. Results: Compared with pre-hibernation, body weight decreased by about 10% per hibernation month and muscle wet weight was not altered. However, muscle-to-body weight ratio increased significantly. Both type I and type II fiber CSA increased by about 8% during hibernation, with no obvious influence of hibernation duration. Hibernation caused a slight but significant decrease in both ATPase activity and the percentage of type II fibers. 2-4 days after arousal, both fiber CSA and fiber type distribution returned to pre-hibernation levels. No type II fiber sub-type can be identified in dauria ground squirrel EDL samples. Conclusion: We report first data on EDL fiber type distribution and hibernation effects in dauria ground squirrels. EDL did not show any sign of atrophy over the 3-month winter dormancy. These results suggest that a potential mechanism exists in hibernators that would allow them to prevent muscle atrophy for the prolonged disuse.
keywords: Dauria ground squirrels extensor digitorum longus myosin ATPase hibernation
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冬眠对达乌尔黄鼠(Spermophilus dauricus)趾长伸肌形态结构及肌纤维类型的影响
摘要: 目的:探讨冬眠过程中,达乌尔黄鼠(Spermophilus dauricus)趾长伸肌(extensor digitorum longus, EDL)的肌肉湿重、肌纤维横截面积(cross-sectional area,CSA)及肌纤维mATP酶活性的变化。方法:选用冬眠前、冬眠中(冬眠1、2个月)、和出眠2-4天的达乌尔黄鼠,测量其EDL的湿重及湿重体重比,以Ca2+-ATPase法测定EDL的mATP酶活性,计算?型和П型肌纤维的比例,测定EDL中?型和П型肌纤维的横截面积。结果:(1)与冬眠前相比, 冬眠黄鼠的体重逐渐降低,平均每冬眠一个月体重降低约10%,EDL湿重无明显变化,肌重体重比明显增加。(2) 冬眠黄鼠EDL的mATP酶活性较冬眠前明显升高,II型肌纤维比例明显下降,I型肌纤维比例明显增加;肌纤维的CSA增大约8%,且这种增大与冬眠中?型肌纤维的比例的增加均与冬眠时间长短无关,不会随着冬眠时间的延长出现差异;(3)出眠2-4天的黄鼠,其EDL中I、П型肌纤维比例及肌纤维CSA均基本恢复至冬眠前水平。结论:达乌尔黄鼠在本实验室的冬眠屋中历经3个多月的冬眠后,EDL不仅没有发生萎缩,而且其肌纤维横截面积较冬眠前还出现了明显的增大,显然,冬眠黄鼠体内存在抗废用性肌萎缩机制。
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冬眠对达乌尔黄鼠(Spermophilus dauricus)趾长伸肌形态结构及肌纤维类型的影响
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