FAILURE OF THE CONTRACTILE PROCESS IN FATIGUE

疲劳时收缩过程失败

• 批准号: 3161033
• 负责人: THOMAS M NOSEK
• 金额: $ 29.96万
• 依托单位: AUGUSTA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1996-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3161033
• 关键词: Rana; calcium flux; creatine; cyclic AMP; fatigue; flame photometry; fresh water environment; lactates; microspectrophotometry; muscle cells; muscle contraction; muscle metabolism; muscle proteins; myofibrils; phosphates; radioimmunoassay; sarcoplasmic reticulum; single cell analysis

Fast, glycolytic muscle fibers are typically subjected to stimulation of short duration and high intensity. In response, force reversibly declines; i.e. the fibers fatigue. In well-motivated subjects, the cause of this type of fatigue resides within the muscle rather than in the central nervous system, peripheral nerves, or neuromuscular junction. Therefore, it has been appropriately studied in isolated muscle fibers. The cellular basis for fatigue is not yet well understood, partly because models have been constructed from studies on a wide range of species, preparations, conditions, and fatiguing protocols that consider only restricted aspects of the problem. Ca2+ uptake and release by the sarcoplasmic reticulum (SR) and the response of the contractile apparatus to the released Ca2+ are likely sites at which impairment may produce fatigue. What is the immediate cause of fatigue; what is the agent or agents that directly affect the SR and contractile proteins? This question has not as yet been answered. Our working hypothesis is that the changes in contractile force associated with fatigue and recovery from fatigue are paralleled by changes in the intracellular milieu and that these changes are causative. To test this hypothesis, we will carry out a two part study: 1) We will measure the intracellular concentration of the constituents of the milieu that we think most likely cause fatigue, under the following conditions: i) control; ii) during fatigue; iii) with recovery from fatigue. The constituents are: a) ATP, AMP, IMP, creatine, lactate, inorganic phosphate, phosphocreatine, glycogen, and H+ by biochemical analysis; b) K+ and Na+ by flame photometry; c) inositol (1,4,5)trisphosphate by specific binding assay; d) cAMP by radioimmunoassay; e) Mg2+, ADP, ionic strength, and free energy of ATP hydrolysis by computation. 2) We will determine the influences these milieu changes have on: a) the Ca2+ uptake, and Ca2+ release in skinned fibers and SR triads, terminal cisternae, and longitudinal SR, b) the contractile apparatus by measuring the contractile properties of skinned single fibers. the studies utilizing skinned fibers will be carried out on preparations from control and fatigued muscles. These experiments will provide a better understanding of the cellular basis of fatigue than previous studies because this complex problem can only be successfully addressed with a multifaceted approach which incorporates both biochemical and physiological techniques that are applied to the same experimental model under the same experimental conditions. They will also determine whether the deficiencies with fatigue are the result of defects in the organelles themselves or whether it is the intracellular milieu that interferes with the normal function of the cell components.

快速，糖酵解肌肉纤维通常受到刺激 短持续时间和高强度。 作为回应，迫使强迫 下降；即纤维疲劳。 在动机良好的主题中，原因 这种类型的疲劳位于肌肉中，而不是 中枢神经系统，周围神经或神经肌肉连接。 因此，已经在孤立的肌肉纤维中进行了适当的研究。 疲劳的细胞基础尚未得到很好的理解，部分是因为 模型是根据对广泛物种的研究构建的， 仅考虑的准备，条件和疲劳协议 问题的限制方面。 CA2+吸收并释放 肌质网（SR）和收缩设备的响应 对于发布的CA2+，可能会产生损害的地点 疲劳。 疲劳的直接原因是什么？代理是什么或 直接影响SR和收缩蛋白的代理？ 这 问题尚未回答。 我们工作的假设是 与疲劳和恢复相关的收缩力的变化 疲劳与细胞内环境的变化以及 这些变化是病因。 为了检验这一假设，我们将携带 进行两部分研究： 1）我们将测量成分的细胞内浓度 我们认为最有可能导致疲劳的环境 以下条件：i）控制； ii）在疲劳期间； iii）恢复 来自疲劳。 成分是：a）ATP，AMP，IMP，肌酸， 乳酸，无机磷酸盐，磷酸蛋白，糖原和H+ 生化分析； b）k+和na+通过火焰光度法； c）肌醇 （1,4,5）通过特异性结合测定法； d）营地 放射免疫分子； e）MG2+，ADP，离子强度和ATP的自由能 通过计算水解。 2）我们将确定这些环境变化对：a） Ca2+摄取，在皮肤纤维和SR三合会中释放Ca2+终端 Cisternae和纵向SR，b）通过测量收缩设备 皮肤单纤维的收缩特性。 研究 使用皮肤纤维将在控制的准备工作中进行 和疲劳的肌肉。 这些实验将更好地了解细胞 疲劳的基础比以前的研究，因为这个复杂的问题可以 仅通过多方面的方法成功解决 合并生化和生理技术 在同一实验下应用于相同的实验模型 状况。 他们还将确定是否有缺陷 疲劳是细胞器本身缺陷的结果 是细胞内环境会干扰正常功能 细胞成分。