Studying Sodium Channel Gating in Heterologous Expression Systems
Voltage-gated sodium channels (Navs) are essential for the initiation and propagation of action potentials in most excitable tissues, such as neurons or cardiac myocytes. Mutations in Navs are linked to several severe conditions, such as pain syndromes, epilepsy, and cardiac arrhythmias and these ion channels are therefore among the most promising drug targets. The development of Nav modulators is complicated by the intricate gating mechanisms of these ion channels. They activate extremely quickly and subsequently inactivate equally fast. There are several additional gating modes that are physiologically relevant and that may be involved in the pathophysiology of numerous conditions, such as a variety of pain syndromes.
Whole-cell voltage clamp is a valuable technique to study the different gating modes of Navs and their possible physiological roles. It can be conducted in a variety of tissue preparations; however, for the basic investigation of Nav activity, heterologous expression systems offer numerous advantages. The fast kinetics of Nav activity make it difficult to accurately measure these events. The following chapter therefore aims to provide the necessary steps and protocols in order to study Nav gating.
Key wordsVoltage-gated sodium channel Nav Patch-clamp electrophysiology Voltage clamp HEK cells
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