FLUCTUATIONS IN THE INTENSITY OF LIGHT SCATTERED THROUGH DIASTOLIC CARDIAC MUSCLL

我们发现散射光强度的波动 （SLIF）存在于离体大鼠心室肌中，即使在 以前被认为是静止的状态。 后续 实验表明，SLIF高度依赖于钙 电池的负载，并且可以可逆地终止（1）， 维持肌丝中恒定的钙浓度 （2）咖啡因在完整纤维中的作用。 这些 结果表明，细胞肌浆 钙离子浓度在钙离子中振荡， 肌丝，它调制激光束， SLIF。 这种肌丝的运动是不同步的， 细胞和细胞之间，导致小程度的舒张力 或肌肉的“张力”。 其他实验有 在心房、心室和传导组织中证实了SLIF， 包括人类在内的一系列哺乳动物物种， 这种现象在可兴奋的心脏组织中的普遍性。 我们 直接证明了这些钙振荡， 细胞内注射发光蛋白水母发光蛋白 并模拟了非均匀钙振荡对 紧张力 我们还证明了SLIF在 完整的灌注心脏，并表明它与 钙依赖性紧张 在我们最近的研究中， 确定了肌丝运动的具体特征 导致SLIF。 我们还发现缺血抑制了 自发性钙释放和再灌注加重了其作用。

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 indicate that cellular myoplasmic calcium concentration oscillates in diastole, producing 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 determined the specific characteristics of myofilament motion that cause SLIF. We have also shown that ischemia suppresses spontaneous calcium release and reperfusion exacerbated it.