Sarcomere lesion damage occurs mainly in slow fibers of reloaded rat adductor longus muscles.
Sarcomere lesion damage occurs mainly in slow fibers of reloaded rat adductor longus muscles.
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DOI：
10.1152/jappl.1998.85.3.1017
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发表时间：
1998-09
影响因子：
3.3
通讯作者：
K. Vijayan;J. Thompson;D. Riley
中科院分区：
文献类型：
--
作者：
K. Vijayan;J. Thompson;D. Riley
Sarcomere lesions were previously observed with reloading of rat adductor longus muscles after spaceflight and hindlimb unloading (HU). Spaceflown rats displayed more lesioned fibers in the "slow-fiber" region, suggesting a damage-susceptible fiber type. Unloading induces fast myosin expression in some slow fibers, generating hybrid fibers. We examined whether lesion damage differed among slow-, hybrid-, and fast-fiber types in HU-reloaded adductor longus muscles. Temporal HU for 5, 8, 11, 14, and 17 days revealed that hybrid fiber percent, detected by antimyosin immunostaining, peaked at 29 +/- 12% by 14 days. A 14-day HU followed by 12-14 h of voluntary reloading was performed to induce lesions. chi2 analysis showed that slow fibers were preferentially damaged, accounting for 92 +/- 5% of lesioned fibers; hybrid and fast fibers accounted for 7 +/- 4 and <0.5%, respectively. Atrophy did not explain differential lesion damage across fiber types, as slow and hybrid fibers atrophied to a similar extent. Because active myofiber contractions are requisite for lesion formation, selective recruitment of slow fibers most likely explains their damage susceptibility.
