Sodium Current Measurements in HEK293 Cells

Abstract

This protocol is used to measure sodium currents from heterologously transfected cells lines, such as HEK293 cells. Standard whole cell patch clamp technique is used to assess ion channel function. This protocol has been used to study cardiac type Nav1.5 sodium channel, and in particular to compare wild-type and mutant channels related to Brugada Syndrome (BrS). Mutations related to BrS provoke a loss of function of the cardiac sodium channel. This is evidenced by a reduction of sodium current density and/or alterations of the activation or inactivation kinetic parameters, such as a slow recovery from inactivation. These effects could explain the alteration of the cardiac action potential that leads to the characteristic ST elevation observed in the electrocardiogram of the Brugada Syndrome patients. This protocol, with some variations, is suitable for studying other cardiac arrhythmias related to alterations in the cardiac type sodium channel function as well as for studying other voltage-dependent sodium channels.