Electrophysiology Study On Cardiac Membrane Ionic Channel

Cardiac membrane ion channels are very important for maintains of membrane potential, modulation of heart function and also for drug actions. The purpose of this study was to investigate the characterization of membrane ionic channel currents in human atrial and guinea-pig ventricular myocytes and to study on the regulation of drugs on these currents by using the patch clamp whole cell recording techniques.一, study on membrane ionic channel currents in human atrial cellsBecause of species differences, it plays an important role in clinic work to study directly on membrane ionic channel currents in human atrial cells. Specimens of human right atrial appendage were obtained from patients undergoing cardiopulmonary bypass in FuWai hospital. We used the method of enzymatic dispersion to get single rod-shaped , calcium-tolerant cells for electrophysiology study. The characterization of Na⁺, K⁺, Ca²⁺ currents and the regulation of drugs on these currents were investigated by using patch clamp whole cell recording techniques. (1) Recording and the character of the sodium current Atrial cells were depolarized to 0mV for 50 ms from the holdingpotential of -100 mV, a very fast activated and inactivated large inward current was recorded. In order to further demonstrate this is a sodium currents, we substituted TEA (the same concentration as Na⁺) for NaCl in Tyrode solution and found that the current was completely abolished by removing Na⁺. When depolarized cells from -100 mV, a serial inward currents were recorded. It was found that...