INTERNAL MEMBRANE SYSTEM OF ISOLATED CARDIAC CELLS

这一项目的目的是确定横向的 小管和肌浆网在基础电生理中的作用 单个心脏细胞的特性。这将通过确定 基于两者的单个单元的最佳等效电路表示 电学和形态测量。标准电流和 电压钳电生理方法将与 经典的阻抗方法成功地用来做类似的研究 骨骼肌。 将使用等效电路分析来严格评估 电压钳测量离子电流的有效性。电压 钠、钾和钙离子的依赖电导将是 采用大信号和小信号阶跃电压钳位测量。动能 这两个测量的参数将直接与 从白噪声分析的新技术中获得。 膜片钳将被用来比较 具有包含并元结构或区域的表面膜 横管。将使用焦点刺激来寻找低阈值 与早期测量结果类似的收缩反应区域 骨骼肌局部兴奋收缩偶联的研究 横小管的部分。

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.