CONTRACTILE PROPERTIES OF SKELETAL-MUSCLES FROM YOUNG, ADULT AND AGED MICE
CONTRACTILE PROPERTIES OF SKELETAL-MUSCLES FROM YOUNG, ADULT AND AGED MICE
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DOI：
10.1113/jphysiol.1988.sp017279
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发表时间：
1988-10-01
影响因子：
5.5
通讯作者：
FAULKNER, JA
中科院分区：
文献类型：
--
作者：
BROOKS, SV;FAULKNER, JA
在体外25℃条件下，对年轻（2 - 3个月）、成年（9 - 10个月）和老年（26 - 27个月）雄性小鼠的比目鱼肌和趾长伸肌（EDL）进行了比较。我们检验了以下假设：与年轻和成年小鼠的比目鱼肌和趾长伸肌相比，老年小鼠的这些肌肉产生的最大强直收缩力（P0，毫牛）和比肌力（P0，牛/平方厘米）降低，并且收缩时间、半松弛时间或力 - 速度关系无显著差异。对于老年小鼠，比目鱼肌和趾长伸肌的P0分别是成年小鼠相应值的78%和73%。老年小鼠趾长伸肌的比肌力是年轻和成年小鼠所测得的23牛/平方厘米这一数值的78%。对于比目鱼肌，21牛/平方厘米的比肌力不随年龄变化。与年轻和成年小鼠的值相比，老年小鼠比目鱼肌的收缩时间和半松弛时间增加，但比目鱼肌和趾长伸肌的整体力 - 速度关系未改变。从比目鱼肌和趾长伸肌的力 - 速度关系推算出的无负荷缩短的最大速度汇总值分别为4.6和10.1个肌纤维长度/秒。随着年龄增长，趾长伸肌比肌力的降低必定是由于驱动冲程中横桥数量减少，或者每个横桥产生的力降低所致。
Comparisons were made in vitro at 25.degree.C among soleus and extensor digitorum longus (EDL) muscles from young (2-3 months), adults (9-10 months), and aged (26-27 months) male mice. We tested the hypotheses that, compared with soleus and EDL muscles of young and adult mice, those from aged mice developed decreased maximum tetanic force (P0, mN) and specific P0 (N/cm2), and that no significant differences occur for contraction time, half-relaxation time, or force-velocity relationship. For the aged mice, the P0 of the soleus mucles and EDL muscles were 78 and 73% respectively of the values for adult mice. the specific P0 of EDL muscles of aged mice was 78% of the value of 23 N/cm2 obtained for young and adult mice. For soleus muscles, the specific P0 of 21 N/cm2 did not change with age. Compared to values for young and adult mice, the contraction and half-relaxation times of soleus mucles from aged mice were increased, but the overall force-velocity relationships of soleus and EDL muscles did not change. The pooled values for the maximum velocity of unloaded shortening extrapolated from the force-velocity relationship of soleus and EDL mucles were 4.6 and 10.1 fibre lengths/s, respectively. The decrease in the specific P0 of the EDL muscle with aging must result from either a decrease in the number of cross-bridges in the driving stroke or a decrease in the force developed by each cross-bridge.