Muscle calcium transient. Effect of post-stimulus length changes in single fibers.
Muscle calcium transient. Effect of post-stimulus length changes in single fibers.
复制标题
肌肉钙瞬变。
DOI：
10.1085/jgp.83.1.75
复制
发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Gordon,AM
中科院分区：
文献类型：
--
作者：
Ridgway,EB;Gordon,AM
我们研究了刺激后长度的变化对电压钳制的、注射水飞蓟素的藤壶藤壶单肌纤维的影响。在钙瞬变的下降阶段，当纤维被允许缩短(一小部分)时，就会看到额外的光(额外的钙)。当纤维被拉伸时，则观察到相反的情况。增加缩短的程度会增加额外的钙量，降低温度也是如此。额外的钙可能来自肌丝而不是肌浆网，因为(A)额外的钙与激活程度之间有很强的相关性；(B)额外的钙与改变长度后重新形成的力的大小有很强的相关性；(C)额外的钙出现的时间过程介于游离钙浓度和力的时间过程之间。我们认为(A)与激活的肌原纤维蛋白结合的钙对肌肉长度或肌力敏感，(B)存在一个结合钙池(激活钙)，它随着游离钙浓度和肌力之间的时间进程而消长。
We examined the effects of post-stimulus length changes on voltage-clamped, aequorin-injected single muscle fibers from the barnacle Balanus nubilus. Extra light (extra calcium) is seen when the fiber is allowed to shorten (a small percentage) during the declining phase of the calcium transient. The opposite is observed when the fiber is stretched. Increasing the extent of shortening increases the amount of extra calcium, as does decreasing the temperature. The extra calcium probably comes from the myofilaments and not from the sarcoplasmic reticulum because (a) there is a strong correlation between the extra calcium and the level of activation;(b) there is a strong correlation between the extra calcium and the amount of force redeveloped after a length change; and (c) the time course of the appearance of the extra calcium is intermediate between that of the free calcium concentration and that of force. We suggest (a) that the calcium binding to the activating myofibrillar proteins is sensitive to muscle length or muscle force, and (b) that there is a pool of bound calcium (activating calcium) that waxes and wanes with a time course intermediate between the free calcium concentration and force.