Aging effects on passive resistive torque in the rat ankle joint after lengthening contractions
Aging effects on passive resistive torque in the rat ankle joint after lengthening contractions
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DOI：
10.1007/s00776-008-1216-8
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发表时间：
2008-05-01
影响因子：
1.7
通讯作者：
Nakajima, Hiroyuki
中科院分区：
文献类型：
--
作者：
Ochi, Eisuke;Nakazato, Koichi;Nakajima, Hiroyuki
背景。本研究的目的是评估老化是否会影响(1)延长收缩（LCs）后的关节僵硬感；(2)踝关节被动电阻扭矩（PRT）；(3)和连接蛋白（titin）在内侧腓肠肌（MG）中的异构体组成。实验采用麻醉幼龄Wistar大鼠（9周龄）和成年Wistar大鼠（35周龄），每组6只。通过皮肤电极电致强直收缩，同时踝关节强制背屈（角速度15度/秒，0度-45度），对MG肌进行单次LCs。测量踝关节（30度和45度）的静态PRT以评估关节刚度。这些参数一直测量到治疗后10天。采用低孔隙率2%聚丙烯酰胺凝胶电泳法测定连接蛋白异构体的肌肉伸展性。成年大鼠的平均静态PRT明显高于年轻大鼠。连接蛋白异构体分析显示，成年鼠比年轻鼠含有更多的-连接蛋白。LCs后，青年组踝关节静态PRT逐渐升高，直至第4天，而成年组在实验期间无明显变化。我们得出结论：(1)成年大鼠的关节刚度大于幼鼠，与人类研究相似；(2)接头刚度增大可能是由于连接异型组成所致；(3)年轻大鼠MG肌lc后关节僵硬更明显。
Background. The aim of this study was to evaluate whether aging affects (1) the sensation of joint stiffness after lengthening contractions (LCs); (2) passive resistive torque (PRT) of the ankle joint; (3) and the connectin (titin) isoform composition in the medial gastrocnemius (MG) muscle.Methods. Anesthetized young (9 weeks) and adult (35 weeks) Wistar rats (n = 6 per group) were used in the present study. A single bout of LCs was performed on the MG muscle with a combination of electrically induced tetanic contractions via a skin electrode and simultaneous forced dorsiflexion of the ankle joint (angular velocity 15 degrees/s, 0 degrees-45 degrees). Static PRT of the ankle joint (at 30 degrees and 45 degrees) was measured to evaluate joint stiffness. These parameters were measured until 10 days after treatment. The connectin isoform was measured as muscle extensibility employing low-porosity 2% polyacrylamide gel electrophoresis.Results. The averaged static PRT was significantly higher in adult rats than in young rats. Connectin isoform analysis revealed that the adult group contained larger amounts of beta-connectin than did the young rats. After the LCs, static PRT of the ankle joint gradually increased until day 4 in the young group, whereas the adult group did not show a significant change during the experimental period.Conclusions. We concluded that (1) joint stiffness of adult rats is greater than in young rats, similar to human studies; (2) the increased joint stiffness may be due to connectin isoform composition; and (3) joint stiffness after MG muscle LCs is more apparent in young rats.