FLUCTUATIONS IN THE INTENSITY OF LIGHT SCATTERED THROUGH DIASTOLIC CARDIAC MUSCLE

我们发现，散射光强度起伏(SLIF)是 即使在以前的条件下，也存在于分离的大鼠心肌中 被认为是静止的。随后的实验表明，SLIF是 高度依赖于细胞的钙负荷，并且可以可逆地 通过保持细胞内钙浓度恒定而终止(1) 有皮纤维中的肌丝间隙或(2)咖啡因作用下完整纤维中的肌丝间隙。 这些结果被解释为表明细胞肌浆 钙浓度在舒张期振荡，产生运动 肌丝，它调制激光束，并导致SLIF.这 肌丝在细胞内和细胞之间是不同步的运动， 在肌肉中产生少量的舒张力或“张力”。 更多的实验已经证明，在心房，心室和 一系列哺乳动物的传导组织，包括人类和 表明这一现象在可兴奋的心脏组织中具有普遍性。 我们已经直接证明了这些钙振荡利用 细胞内注射化学发光蛋白Aequorin并模拟 异质性钙振荡对紧张力的影响。我们有 也证明了在完整的灌流心脏中存在SLIF 已经表明，它与钙依赖的语气是一致的。尽我们最大的努力 最近的研究，我们已经确定了特定的特征 导致滑脱的肌丝运动。我们还表明，脑缺血 抑制自发性钙释放，再灌流加重。

We have discovered that scattered light intensity fluctuations (SLIF) are present in isolated rat ventricular muscle even under conditions formerly considered to be quiescent. Subsequent experiments indicated that SLIF are highly dependent on calcium loading of the cell and could be reversibly terminated (1) by maintaining constant calcium concentration in the myofilament space in skinned fibers or (2) in intact fibers by caffeine. These results were interpreted to indicated that cellular myoplasmic calcium concentration oscillates in diastole, producting motion of the myofilaments, which modulates the laser beam and results in SLIF. This myofilament motion which is asynchronous within a cell, and among cells, results in a small degree of diastolic force or "tone" in the muscle. Additional experiments have demonstrated SLIF in atrial, ventricular, and conduction tissues in a range of mammalian species including man and indicate the universality of this phenomenon in excitable cardiac tissues. We have directly demonstrated these calcium oscillations utilizing intracellular injects of the chemiluminescent protein, aequorin and modeled the effect of heterogeneous calcium oscillation on tonic force. We have also demonstrated the presence of SLIF in the intact perfused heart and have shown that it covaries with calcium-dependent tone. In our most recent studies we have determine the specific characteristics of myofilament motion that cause SLIF. We have also shown that ischemia suppresses spontaneous calcium release and reperfusion exacerbated it.