CA INDUCED CA RELEASE FROM STRIATED MUSCLE

克氏原螯虾的兴奋-收缩偶联机制 骨骼肌更接近哺乳动物的心肌 比脊椎动物的骨骼肌更依赖于 Ca ~（2+）诱导的肌浆网Ca ~（2+）释放（CICR）。 我们使用小龙虾肌肉作为CICR工作模型的初步结果 已经导致了一个新的假设的形成， 分离t-小管和SR的连接间隙，以解释CICR如何 由通过t小管的内向Ca 2+电流严格控制 膜，同时保持相对不敏感的Ca 2+释放从 Sr.本申请寻求： 1)利用小龙虾肌肉实验的便利性 详细研究了CICR工艺， 2)进行计算机模拟的小龙虾E-C耦合作为一个特定的 局部控制理论的例子， 3)为了将这些发现与以下方面的等效实验结果进行比较， 从大鼠心室分离的肌细胞。 小龙虾肌肉实验将包括直接演示 肌节内钙浓度梯度，数量测定 激活每个ryanodine受体所需的Ca 2+离子， 区分两种替代控制模型，一种是首次提出的 被私家侦探另一个是合作研究者。 Ca 2+运动在假定的子域以及在其余的 连接间隙将被建模，以确定两个Ca 2+的位置 差距内的敏感位点。 将在分离的心肌细胞上进行平行实验 结合笼内Ca ~（2+）实验和I（Ca）失活研究， 和SR Ca 2+释放失活，以确定我们的小龙虾模型 可以解释心肌中的CICR，以及它是否被 心脏中兰尼碱受体的存在与 二氢吡啶受体。

The mechanism of excitation-contraction (E-C) coupling in crayfish skeletal muscle more closely resembles that of mammalian cardiac muscle than that of vertebrate skeletal muscle in terms of its dependence on Ca2+-induced Ca2+ release (CICR) from the sarcoplasmic reticulum (SR). Our preliminary results using crayfish muscle as a working model for CICR have led to the formulation of a new hypothesis of a subdomain within the junctional gap that separates t-tubule and SR to explain how CICR can be tightly controlled with inward Ca2+ currents through the t-tubule membrane while remaining relatively insensitive to Ca2+ released from the SR. The present application seeks: 1) to take advantage of the ease of experimentation with crayfish muscle to study the process of CICR in detail, 2) to perform computer modelling of crayfish E-C coupling as a specific example of local control theory, 3) to compare these findings with results of equivalent experiments on myocytes isolated from rat ventricle. Crayfish muscle experiments will include direct demonstration of intrasarcomeric Ca2+ concentration gradients, determination of the number of Ca2+ ions required to activate each ryanodine receptor, and a test to discriminate between two alternative control models, one first proposed by the P.I. and the other by the coinvestigator. Ca2+ movements in the postulated subdomain as well as in the rest of the junctional gap will be modeled to pinpoint the locations of the two Ca2+ sensitive sites within the gap. Parallel experiments will be carried out on isolated cardiac myocytes together with caged Ca2+ experiments, and studies of I(Ca) inactivation and SR Ca2+ release inactivation to determine how well our crayfish model of CICR may explain CICR in heart muscle and whether it is modified by the presence in heart of ryanodine receptors not intimately associated with dihydropyridine receptors.