ROLES OF MYOFILAMENT BOUND CALCIUM IN MUSCLE CONTRACTION

肌丝结合钙在肌肉收缩中的作用

• 批准号: 2225537
• 负责人: MARIE E CANTINO
• 金额: $ 9.37万
• 依托单位: UNIVERSITY OF CONNECTICUT STORRS
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-01-01 至 1997-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2225537
• 关键词: SDS polyacrylamide gel electrophoresis; actins; animal tissue; calcium binding protein; calcium flux; cryoscience; electron probe spectrometry; muscle contraction; myocardium; myofibrils; myosins; sarcomeres; striated muscles; tissue /cell preparation; troponin

The overall long term goal of this research is to understand the mechanisms by which elevation in myoplasmic free calcium regulates contraction of vertebrate striated muscle and in particular, to explore the ways in which calcium binding to myofilaments may modulate and be modulated by the contractile event. The hypothesis to be examined proposes that calcium binding to the thin filament is enhanced by the attachment of cycling crossbridges to actin in both cardiac and skeletal muscle. This proposed phenomenon has been cited as a molecular basis for the Frank- Starling relation, and may underlie other features of the contractile event in striated muscle. This hypothesis will be tested by mapping the distribution of calcium along the sarcomere using quantitative electron probe X-ray microanalysis (EPXMA) and elemental imaging of freeze dried cryosections of glycerinated rabbit psoas muscles, frog semitendinosis, and rabbit and frog ventricular trabeculae. Fibers will be frozen in solutions with or without MgATP and with varying levels of free calcium. EPXMA of fibers following partial extractions of TnC and myosin regulatory light chains would be used to identify the source of any observed enhancement in calcium binding in the overlap region. Orthovanidate or N- phenylmaleimide will be used to determine characteristics of the attachments with lead to this phenomenon. The spatial extent of any calcium enhancement will be examined to determine whether the thin filament behaves as a single unit with respect to calcium binding, or whether other models predicting a shorter range of cooperativity are favored. Also to be examined is whether there are intrinsic variations in calcium affinity along the thin filament, independent of interactions between actin and myosin. These studies will provide insight into the fundamental mechanisms which modulate activation of force in skeletal and cardiac muscle.

这项研究的总体长期目标是了解 肌质游离钙升高的调节机制 脊椎动物横纹肌的收缩，特别是探索 钙与肌丝结合的调节方式 由收缩事件调节。要检验的假设提出 钙与细丝的结合通过附着而增强 在心肌和骨骼肌中循环横桥至肌动蛋白。这 所提出的现象已被引用为弗兰克- Starling 关系，并且可能是收缩的其他特征的基础 横纹肌中的事件。该假设将通过映射来检验 使用定量电子测量钙沿肌节的分布 冻干物的探针 X 射线微量分析 (EPXMA) 和元素成像 甘油冷冻兔腰肌、青蛙半腱变性、 以及兔子和青蛙的心室小梁。纤维将被冻结在 含有或不含 MgATP 以及不同水平游离钙的溶液。 部分提取 TnC 和肌球蛋白调节后的纤维 EPXMA 轻链将用于识别任何观察到的来源 重叠区域的钙结合增强。正钒酸盐或 N- 苯基马来酰亚胺将用于确定的特性 附件导致这种现象。任意空间范围 将检查钙强化以确定是否薄 就钙结合而言，细丝表现为单个单元，或 其他模型是否预测更短的合作范围 受到青睐。还需要检查的是是否存在内在差异 沿细丝的钙亲和力，与相互作用无关 肌动蛋白和肌球蛋白之间。这些研究将提供深入了解 调节骨骼和骨骼中力的激活的基本机制 心肌。