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慢性低氧后大鼠比目鱼肌和膈肌肌球蛋白纤维收缩性能的变化。

Changes in contractile properties of skinned single rat soleus and diaphragm fibres after chronic hypoxia.

机构信息

Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, John Dalton Building, Oxford Road, Manchester, M1 5GD, UK.

出版信息

Pflugers Arch. 2010 Oct;460(5):863-73. doi: 10.1007/s00424-010-0866-5. Epub 2010 Aug 10.

Abstract

Hypoxia may be one of the factors underlying muscle dysfunction during ageing and chronic lung and heart failure. Here we tested the hypothesis that chronic hypoxia per se affects contractile properties of single fibres of the soleus and diaphragm muscle. To do this, the force-velocity relationship, rate of force redevelopment and calcium sensitivity of single skinned fibres from normoxic rats and rats exposed to 4 weeks of hypobaric hypoxia (410 mmHg) were investigated. The reduction in maximal force (P(0)) after hypoxia (p=0.031) was more pronounced in type IIa than type I fibres and was mainly attributable to a reduction in fibre cross-sectional area (p=0.044). In type IIa fibres this was aggravated by a reduction in specific tension (p=0.001). The maximal velocity of shortening (V (max)) and shape of the force velocity relation (a/P(0)), however, did not differ between normoxic and hypoxic muscle fibres and the reduction in maximal power of hypoxic fibres (p=0.012) was mainly due to a reduction in P(0). In conclusion, chronic hypoxia causes muscle fibre dysfunction which is not only due to a loss of muscle mass, but also to a diminished force generating capacity of the remaining contractile material. These effects are similar in the soleus and diaphragm muscle, but more pronounced in type IIa than I fibres.

摘要

缺氧可能是衰老和慢性肺、心功能衰竭导致肌肉功能障碍的因素之一。在这里,我们检验了这样一个假设,即慢性缺氧本身会影响比目鱼肌和膈肌的单个纤维的收缩特性。为此,我们研究了常氧大鼠和 4 周低压缺氧(410mmHg)暴露大鼠的单个肌纤维的力-速度关系、力重发展率和钙敏感性。缺氧后最大力(P(0))的降低(p=0.031)在 IIa 型纤维中比 I 型纤维更为明显,主要归因于纤维横截面积的减少(p=0.044)。在 IIa 型纤维中,这因比张力的降低而加重(p=0.001)。然而,最大缩短速度(V (max))和力速度关系的形状(a/P(0))在常氧和缺氧肌纤维之间没有差异,并且缺氧纤维的最大功率降低(p=0.012)主要是由于 P(0)的降低。总之,慢性缺氧会导致肌肉纤维功能障碍,这不仅是由于肌肉质量的丧失,还由于剩余收缩物质的产生能力下降。这些影响在比目鱼肌和膈肌中相似,但在 IIa 型纤维中比 I 型纤维更为明显。

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