N-benzhydryl quinuclidine compounds are a potent and Src kinase-independent inhibitor of NALCN channels.

Suyun Hahn, So Woon Kim, Ki Bum Um, Hyun Jin Kim, Myoung Kyu Park

British journal of pharmacology 2020 Aug

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NALCN is a Na+ leak, GPCR-activated channel that regulates the resting membrane potential and neuronal excitability. Despite numerous possible roles for NALCN in both normal physiology and disease processes, lack of specific blockers hampers further investigation. The effect of N-benzhydryl quinuclidine compounds on NALCN channels was demonstrated using whole-cell patch-clamp recordings in HEK293T cells overexpressing NALCN and acutely isolated nigral dopaminergic neurons that express NALCN endogenously. Src kinase activity was measured using a Src kinase assay kit, and voltage and current-clamp recordings from nigral dopaminergic neurons were used to measure NALCN currents and membrane potentials. N-benzhydryl quinuclidine compounds inhibited NALCN channels without affecting TRPC channels, another important route for Na+ leak. In HEK293T cells overexpressing NALCN, N-benzhydryl quinuclidine compounds potently suppressed muscarinic M3 receptor-activated NALCN currents. Structure-function relationship studies suggest that the quinuclidine ring with a benzhydryl group imparts the ability to inhibit NALCN currents regardless of Src family kinases. Moreover, N-benzhydryl quinuclidine compounds inhibited not only GPCR-activated NALCN currents but also background Na+ leak currents and hyperpolarized the membrane potential in native midbrain dopaminergic neurons that express NALCN endogenously. These findings suggest that N-benzhydryl quinuclidine compounds have a pharmacological potential to directly inhibit NALCN channels and could be a useful tool to investigate functions of NALCN channels. © 2020 The British Pharmacological Society.

Citation

Suyun Hahn, So Woon Kim, Ki Bum Um, Hyun Jin Kim, Myoung Kyu Park. N-benzhydryl quinuclidine compounds are a potent and Src kinase-independent inhibitor of NALCN channels. British journal of pharmacology. 2020 Aug;177(16):3795-3810