Why the study?
Nav1.5 is the primary cardiac voltage-gated Na+ channel and a major target for class I antiarrhythmic agents, but the structural basis for pore blockade by quinidine remained to be resolved.
The cryo-EM structure of human Nav1.5 bound to quinidine reveals the molecular basis for pore blockade by class Ia antiarrhythmic drugs.
No immediate change to quinidine use; extends atomic understanding of Na v 1.5 blockade for future drug design.
Na v 1.5, the primary voltage‐gated Na + (Na v ) channel in heart, is a major target for class I antiarrhythmic agents. Here we present the cryo‐EM structure of full‐length human Na v 1.5 bound to quinidine, a class Ia antiarrhythmic drug, at 3.3 Å resolution. Quinidine is positioned right beneath the selectivity filter in the pore domain and coordinated by residues from repeats I, III, and IV. Pore blockade by quinidine is achieved through both direct obstruction of the ion permeation path and induced rotation of an invariant Tyr residue that tightens the intracellular gate. Structural comparison with a truncated rat Na v 1.5 in the presence of flecainide, a class Ic agent, reveals distinct binding poses for the two antiarrhythmics within the pore domain. Our work reported here, along with previous studies, reveals the molecular basis for the mechanism of action of class I antiarrhythmic drugs.
No takes yet. Share an insight, caveat, or question.
Li et al. (2021) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: