Voltage-clamp-based methods for the detection of constitutively active acetylcholine-gated I(K,ACh) channels in the diseased heart.

Vagal nerve stimulation can promote atrial fibrillation (AF) that requires activation of the acetylcholine (ACh)-gated potassium current I(K,ACh). In chronic AF (cAF), I(K,ACh) shows strong activity despite the absence of ACh or analogous pharmacological stimulation. This receptor-independent, constitutive I(K,ACh) activity is suggested to represent an atrial-selective anti-AF therapeutic target, but the underlying molecular mechanisms are unknown. This chapter provides an overview of the voltage-clamp techniques that can be used to study constitutive I(K,ACh) activity in atrial myocytes and summarizes briefly the current knowledge about the potential underlying mechanism(s) of constitutive I(K,ACh) activity in diseased heart.