Enzymatic alterations in single type IIB skeletal muscle fibers with inactivity and exercise in 12- and 30-month-old rats.
Enzymatic alterations in single type IIB skeletal muscle fibers with inactivity and exercise in 12- and 30-month-old rats.
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12 个月和 30 个月大的大鼠不活动和运动时单一 IIB 型骨骼肌纤维的酶促变化。
DOI：
10.1007/bf03324461
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发表时间：
2002
影响因子：
4
通讯作者：
Thompson,LaDoraV
中科院分区：
文献类型：
--
作者：
Groskreutz,JonJ;Thompson,LaDoraV
本研究的目的是观察增龄、不活动和负重运动对腓肠肌外侧头浅表区快抽动的单一IIB型骨骼肌纤维(IIB型纤维)的影响。具体地说，本研究比较了成年和老年Fischer 344棕色挪威F1杂交大鼠(12个月和30个月龄)后肢减重7天(HU)、间歇负重7天(HU-Ex)和笼养对照(C)后IIB型纤维的生化特性。生化指标包括总乳酸脱氢酶(LDH)和β羟基酰基辅酶A脱氢酶活性(BHAD)，以摩尔/μg/小时干重表示。用SDS-PAGE对肌球蛋白重链异构体进行纤维分型。随着年龄的增长，IIB型纤维中乳酸脱氢酶的活性从52.0±3.4nmoles/μg/hr(12月龄)下降到39.5±2.9nmoles/μg/hr(30月龄)。在HU作用下，12月龄动物IIB型纤维的乳酸脱氢酶活性增加了22%(52.0±3.4至66.4±3.2nmoles/μg/hr)，而30月龄动物IIB型纤维的乳酸脱氢酶活性无明显变化。在HU-Ex后，12月龄动物IIB型纤维的乳酸脱氢酶活性与HU动物的IIB型纤维无显著差异，而30月龄动物IIB型纤维的乳酸脱氢酶活性显著增加(38.1±2.9nmoles/μg/hr)和HU-Ex。方差分析揭示了年龄和条件之间的交互作用，表明成年和老年动物的IIB型纤维对不活动有不同的生化反应。在不同的实验条件下，BHAD的酶活性没有差异。结果表明，IIB型纤维的总LDH酶活性随着年龄的增加而降低，提示生化谱随年龄的变化而变化。此外，单个骨骼肌纤维的适应是年龄相关的。
The purpose of the present study was to examine the effects of aging, inactivity and weight-bearing exercise on fast-twitch single Type IIB skeletal muscle fibers from the superficial region of the lateral head of the gastrocnemius (Type IIB fibers). Specifically, this study compared the biochemical properties of Type IIB fibers after 7 days of hindlimb unweighting (HU), 7 days of HU with intermittent weight-bearing (HU-Ex), and cage control (C) from adult and aged Fischer 344 Brown Norway F1 Hybrid rats (12- and 30-month old). Biochemical measurements included total lactate dehydrogenase (LDH) and β-hydroxy-acyl-coenzyme A dehydrogenase activities (BHAD), expressed in nmoles/μg/hr dry weight. Fiber-typing for myosin heavy chain isoform was determined by SDS-PAGE. With age, LDH activity in Type IIB fibers decreased from 52.0±3.4 nmoles/μg/hr (12-month old) to 39.5±2.9 nmoles/μg/hr (30-month old). Following HU, LDH activity of single Type IIB fibers increased by 22% (52.0±3.4 to 66.4±3.2 nmoles/μg/hr) in the 12-month-old animals, whereas no difference was observed with HU in the Type IIB fibers of the 30-month-old animals. Following HU-Ex, LDH activity of Type IIB fibers in the 12-month-old animals was not significantly different from that of Type IIB fibers from HU animals, whereas a significant increase was observed (38.1±2.9 to 51.8±3.1 nmoles/μg/hr) in Type IIB fibers of 30-month-old animals, for HU and HU-Ex, respectively. Analysis of variance revealed an interaction between age and condition, indicating that Type IIB fibers from adult and aged animals have a different biochemical response to inactivity. The enzyme activities for BHAD were not different between the experimental conditions. The results demonstrate that the total LDH enzyme activities of the Type IIB fibers decrease with age, suggesting an age-related shift in the biochemical profile. Further, single skeletal muscle fiber adaptation is age-dependent.