INTERNAL MEMBRANE SYSTEM OF ISOLATED CARDIAC CELLS

该项目的目的是确定横向 小管和肌浆网在基本的电生理活动中起着重要作用。 单个心脏细胞的特性。 这将通过确定 最佳等效电路表示的单个细胞的基础上， 电学和形态学测量。 标准电流和 电压钳电生理学方法将与 经典的阻抗方法成功地用于做类似的研究 骨骼肌。 等效电路分析将用于严格评估 离子电流的电压钳测量的有效性。 的电压 钠、钾和钙离子的依赖电导将是 用大信号和小信号阶跃电压箝位测量。 动力学 这两个测量的参数将直接与那些 从白色噪声分析的新技术获得。 膜片钳将用于比较 表面膜的区域含有二元结构或 横小管 局灶刺激将用于寻找低阈值 收缩反应的区域类似于早期的测量结果， 在骨骼肌上显示兴奋-收缩偶联， 横小管的一部分

The purpose of th is project is to determine the role which the transverse tubules and sarcoplasmic reticulum play in the basic electrophysiological properties of single heart cells. This will be done by determining the best equivalent circuit representation of an individual cell based on both electrical and morphological measurements. The standard current and voltage clamp electrphyciological methods will be used in conjuction with the classical impedance methods successfully used to do similar studies on skeletal muscle. The equivalent circuit analysis will be used to rigorously assess the validity of voltage clamp measurements of ionic currents. The voltage dependent conductance of sodium, potassium, and calcium ions will be measured with large and small signal step voltage clamps. The kinetic parameters of these two measurements will be directly compared with those obtained from the new technique of white noise analysis. The patch clamp will be used to compare the passive properties of the surface membrane with regions containing either dyadic structure or transverse tubules. Focal stimulation will be used to find low threshold regions for a contraction response analogous to earlier measurements done on skeletal muscle showing excitation-contraction coupling at the location of the transverse tubules.