EXCITATION-ACTIVATION MECHANISMS IN SMOOTH MUSCLE

平滑肌的兴奋激活机制

• 批准号: 3448660
• 负责人: KRISTINE E KAMM
• 金额: $ 4.73万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-07-01 至 1987-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3448660
• 关键词: calcium channel blockers; elasticity; electrostimulus; gel electrophoresis; muscle cells; muscle contraction; muscle pharmacology; neurotransmitters; phosphorylation; respiratory muscles; smooth muscle; tissue /cell preparation; trachea

The long-term objective of the proposed work is to describe events involved in the physiological regulation of the contraction (relaxation) cycle of the bovine tracheal smooth muscle cell and, eventually, alterations in these processes associated with disease. In order to avoid large diffusional delays in excitation seen with addition of agonist to the bath, cells of the trachealis muscle will be more synchronously activated with the use of selective electrical stimulation of nerves and muscle cells. Entire stimulus response relations will be described for eventual comparisons of matched contractions utilizing intracellular (neural excitation) and extracellular (cell depolarization) sources of calcium. Stimulus frequency will be modulated to simulate activation during physiological rates and types of nervous stimulation. Mechanical characterization (passive and active length-force relations, force-velocity relations and muscle stiffness) of the trachealis preparation will be done to define criteria for estimating degrees of activation of the muscle cells. Muscle strips will be quick-frozen under defined conditions of activation and analyzed using two-dimensional electrophoresis for phosphate content of the 20,000 dalton myosin light chain. Calcium-calmodulin initiation of myosin light chain kinase activity and resultant phosphorylation of myosin is the proposed biochemical mechanism of activation of smooth muscle contraction. Experiments are set forth to test the correlation between mechanical and biochemical activation of cells in neurally stimulated, directly depolarized and paced spontaneously active tissues. An electronic rapid freeze hammer will be used to freeze synchronously activated muscle strips at various times during the first second after stimulation in order to test the hypothesis that rapid muscle shortening (analogous with high actomyosin ATPase rates) will not occur before both 20,000 dalton light chains of myosin are phosphorylated.

拟议工作的长期目标是描述所涉及的事件 在收缩（放松）周期的生理调节中 牛气管平滑肌细胞，最终改变 这些与疾病相关的过程。 为了避免大 通过在浴缸中添加激动剂时，激发的扩散延迟， 气管肌的细胞将与 使用神经和肌肉细胞的选择性电刺激。 最终将描述整个刺激响应关系 利用细胞内的匹配收缩的比较（神经 激发）和钙的细胞外（细胞去极化）来源。 刺激频率将被调制以模拟激活 神经刺激的生理率和类型。 机械的 表征（被动和主动长度关系，力 - 速度 将进行气管准备的关系和肌肉刚度） 定义估计肌肉激活程度的标准 细胞。 肌肉条将在定义的条件下快速冻结 使用二维电泳对磷酸盐进行激活和分析 20,000道尔顿肌球蛋白轻链的内容。 钙 - 钙调蛋白 肌球蛋白轻链激酶活性和结果的启动 肌球蛋白的磷酸化是提出的生化机制 平滑肌收缩的激活。 列出了测试的实验 细胞中机械和生化激活之间的相关性 神经刺激，直接去极化和节奏自发活跃 组织。 电子快速冻结锤将用于冻结 在第一次的不同时间同步激活的肌肉条 刺激后第二，以检验快速肌肉的假设 不会发生缩短（与高肌球蛋白ATPase速率类似） 在将肌球蛋白的20,000个道尔顿光链链磷酸化之前。