EXCITATION-CONTRACTION IN ISOLATED CARDIAC CELLS

收缩、电生理和生化特征 在成年大鼠、家兔和大鼠的心肌细胞中进行了研究。 和豚鼠。 我们开发了一个系统， 测量胞质游离（Ca 2+）细胞长度的变化， 膜电流/电压，具有高的时间分辨率。 系统 使用荧光探针Indo-1监测胞质游离（Ca 2+） 短暂的 细胞长度是从亮场图像测量的， 通过使用视频边缘的光学边缘跟踪方法 检测器和膜电位可以同时监测 使用贴片电极。 最近的显著成果包括： 证明（1）钙电流，而不是去极化每 需要SE或其他去极化介导的事件来触发 Ca 2+从肌浆网释放，引起快速的 胞质（Ca 2+）增加，启动颤搐收缩; (2)抽搐收缩缓慢终末再舒张阶段 与细胞质（Ca 2+）的缓慢衰减时间一致;（3） 延长去极化持续时间可逆转负极化 观察到胞质（Ca 2+）瞬变和收缩的阶梯 在刺激大鼠肌细胞从休息，大概是由 增加细胞Ca 2+负荷。

Contractile, electrophysiological, and biochemical characteristics are studied in dissociated cardiac cells from adult rats, rabbits and guinea pigs. We have developed a system for simultaneous measurement of changes in cytosolic free (Ca2+) cell length and membrane current/voltage, with high time resolution. The system uses the fluorescent probe Indo-1 to monitor cytosolic free (Ca2+) transient. Cell length is measured from the bright-fieid image of the cell by an optical edge tracking method using a video edge detector and the membrane potential can be monitored simultaneously with patch electrodes. Salient recent results include the demonstration that (1) Ca currents rather than depolarization per se or other depolarization mediated events are required to trigger Ca2+ release from the sarcoplasmic reticulum to cause the rapid increase in cytosolic (Ca2+) that initiates the twitch contraction; (2) the slow terminal relengthening phase of a twitch contraction coincides in time with a slow decay of cytosolic (Ca2+); (3) prolonging the duration of depolarization reverses the negative staircase of cytosolic (Ca2+) transients and contraction observed upon stimulation of rat myocytes from rest, presumably by augmenting the cell Ca2+ load.