Identification and characterization of a series of novel HCN channel inhibitors

Area of Science:

• Pharmacology
• Neuroscience
• Cardiology

Background:

• Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are crucial for pacemaker activity in the heart and nervous system.
• Inhibitors of HCN channels are potential therapeutics for conditions like pain, heart failure, arrhythmias, and epilepsy.
• Ivabradine is a clinically approved HCN channel inhibitor used for angina pectoris and heart failure.

Purpose of the Study:

• To design and synthesize novel alkanol amine derivatives as potential HCN channel inhibitors.
• To evaluate the efficacy of these derivatives in inhibiting HCN channel activity.
• To explore the therapeutic potential of identified compounds for neurological and cardiac conditions.

Main Methods:

• Synthesis of eight alkanol amine derivatives.
• Assessment of effects on HCN channels (HCN1, HCN2, HCN4) expressed in COS7 cells using whole-cell patch clamp electrophysiology.
• Evaluation of compound 4e's effect on I_h and action potential firing in mouse small dorsal root ganglion neurons.

Main Results:

• Compound 4e demonstrated potent inhibition of HCN2 channels with an IC₅₀ of 2.9 ± 1.2 µM at -120 mV.
• Compound 4e slowed HCN2 channel activation and caused a hyperpolarizing shift in voltage dependence (ΔV_1/2 = -30.2 ± 2.9 mV).
• Compound 4e showed less potent inhibition against HCN1 (IC₅₀ = 17.2 ± 1.3 µM) and HCN4 (IC₅₀ = 7.3 ± 1.2 µM) channels. It also inhibited I_h and action potential firing in dorsal root ganglion neurons.

Conclusions:

• Compound 4e is a potent inhibitor of HCN2 channels.
• The developed alkanol amine derivatives represent a promising new class of HCN channel inhibitors.
• This study offers a novel strategy for designing and developing effective HCN channel inhibitors for therapeutic applications.