Cardiac cellular electrophysiology, voltage clamp, and patch clamp

Increasing knowledge for the cardiac cellular electrophysiology advances our understanding of cardiac arrhythmia and pathophysiology. Microelectrode recordings in intact tissue preparations and patch clamps in isolated single myocytes provide abundant information about the action potential morphology and pharmacological interventions in cardiomyocytes. Microelectrode recording, an easily learned procedure, can record the action potential with a longer period and avoid the impact due to isolation procedure. However, cellular interactions and complex electrograms from microelectrode recordings may interfere with the data interpretation. In contrast, single-cell recordings provide more direct evidence of action potential and ionic data from current-clamp and voltage-clamp recording. The action potential morphology is caused by the balance of inward and outward currents. Nevertheless, the isolation procedure, cell culture condition and rather short recording period make single-cell recording different from in vivo situations. Through the patch clamp, we can study the ionic mechanism underlying the pacemaker activity of single myocytes. This useful information provides the opportunity to investigate mechanisms of cardiac arrhythmia and develop potential anti-arrhythmia agents.