EFFECT OF SPACEFLIGHT ON SKELETAL-MUSCLE - MECHANICAL-PROPERTIES AND MYOSIN ISOFORM CONTENT OF A SLOW MUSCLE
EFFECT OF SPACEFLIGHT ON SKELETAL-MUSCLE - MECHANICAL-PROPERTIES AND MYOSIN ISOFORM CONTENT OF A SLOW MUSCLE
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DOI：
10.1152/jappl.1994.76.4.1764
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发表时间：
1994-04-01
影响因子：
3.3
通讯作者：
BALDWIN, KM
中科院分区：
文献类型：
--
作者：
CAIOZZO, VJ;BAKER, MJ;BALDWIN, KM
这项研究检测了6天航天飞行后慢速反重力骨骼肌的收缩、生化和组织化学特性的变化。12只雄性SD大鼠随机分为两组：飞行对照组和地面对照组。着陆后约3h，对飞行动物的比目鱼肌进行原位收缩测量。24小时后对对照组动物进行研究。收缩测量包括力-速度关系、力-频率关系和疲劳性。生化测量重点是肌球蛋白重链(MHC)和肌球蛋白轻链图谱。用腺苷三磷酸酶组织化学方法确定慢肌和快肌纤维的横截面积，并确定纤维类型的百分比分布。改变了飞行肌力-速度关系，最大等长张力(P1)降低24%，最大缩短速度增加14%(P<；0.05)。飞行肌肉的力频关系向控制肌肉的右侧移动。在2分钟的疲劳测试结束时，飞行肌肉只产生了34%的P-O，而对照肌肉产生了%的P-O。飞行肌肉表现出IIx型MHC亚型的从头表达，以及慢型I型和快型IIa型MHC亚型的轻微减少。飞行肌肉的组织化学分析显示，快的II型纤维的百分比略有增加，而慢的I型纤维的萎缩程度更大。结果表明，慢速反重力骨骼肌的收缩特性对微重力环境很敏感，并在第一周内开始发生变化。这些变化至少在一定程度上与收缩蛋白表达的数量和类型的变化有关。
This study examined changes in contractile, biochemical, and histochemical properties of slow antigravity skeletal muscle after a 6-day spaceflight mission. Twelve male Sprague-Dawley rats were randomly divided into two groups: flight and ground-based control. Approximately 3 h after the landing, in situ contractile measurements were made on the soleus muscles of the flight animals. The control animals were studied 24 h later. The contractile measurements included force-velocity relationship, force-frequency relationship, and fatigability. Biochemical measurements focused on the myosin heavy chain (MHC) and myosin light chain profiles. Adenosinetriphosphatase histochemistry was performed to identify cross-sectional area of slow and fast muscle fibers and to determine the percent fiber type distribution. The force-velocity relationships of the flight muscles were altered such that maximal isometric tension (P,) was decreased by 24% and maximal shortening velocity was increased by 14% (P < 0.05). The force-frequency relationship of the flight muscles was shifted to the right of the control muscles. At the end of the 2-min fatigue test, the flight muscles generated only 34% of P-o, whereas the control muscles generated 64% of P-o. The flight muscles exhibited de novo expression of the type IIx MHC isoform as well as a slight decrease in the slow type I and fast type IIa MHC isoforms. Histochemical analyses of flight muscles demonstrated a small increase in the percentage of fast type II fibers and a greater atrophy of the slow type I fibers. The results demonstrate that contractile properties of slow antigravity skeletal muscle are sensitive to the microgravity environment and that changes begin to occur within the Ist wk. These changes were at least, in part, associated with changes in the amount and type of contractile protein expressed.