Novel blockers of hyperpolarization-activated current with isoform selectivity in recombinant cells and native tissue

Martina Del Lungo, Michele Melchiorre, Luca Guandalini, Laura Sartiani, Alessandro Mugelli, Istvan Koncz, Tamas Szel, Andras Varro, Maria Novella Romanelli, Elisabetta Cerbai

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Background and Purpose: Selective hyperpolarization activated, cyclic nucleotide-gated channel (HCN) blockers represent an important therapeutic goal due to the wide distribution and multiple functions of these proteins, representing the molecular correlate of f- and h-current (I f or I h). Recently, new compounds able to block differentially the homomeric HCN isoforms expressed in HEK293 have been synthesized. In the present work, the electrophysiological and pharmacological properties of these new HCN blockers were characterized and their activities evaluated on native channels. Experimental Approach: HEK293 cells expressing mHCN1, mHCN2 and hHCN4 isoforms were used to verify channel blockade. Selected compounds were tested on native guinea pig sinoatrial node cells and neurons from mouse dorsal root ganglion (DRG) by patch-clamp recordings and on dog Purkinje fibres by intracellular recordings. Key Results: In HEK293 cells, EC18 was found to be significantly selective for HCN4 and MEL57A for HCN1 at physiological membrane potential. When tested on guinea pig sinoatrial node cells, EC18 (10 μM) maintained its activity, reducing I f by 67% at -120 mV, while MEL57A (3 μM) reduced I f by 18%. In contrast, in mouse DRG neurons, only MEL57A (30 and 100 μM) significantly reduced I h by 60% at -80 mV. In dog cardiac Purkinje fibres, EC18, but not MEL57A, reduced the amplitude and slowed the slope of the spontaneous diastolic depolarization. Conclusions: Our results have identified novel and highly selective HCN isoform blockers, EC18 and MEL57A; the selectivity found in recombinant system was maintained in various tissues expressing different HCN isoforms.

Original languageEnglish
Pages (from-to)602-616
Number of pages15
JournalBritish journal of pharmacology
Volume166
Issue number2
DOIs
Publication statusPublished - May 1 2012

Keywords

  • HCN channels
  • HCN isoforms selectivity
  • I current
  • I current
  • bradycardic agents
  • neuropathic pain

ASJC Scopus subject areas

  • Pharmacology

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    Del Lungo, M., Melchiorre, M., Guandalini, L., Sartiani, L., Mugelli, A., Koncz, I., Szel, T., Varro, A., Romanelli, M. N., & Cerbai, E. (2012). Novel blockers of hyperpolarization-activated current with isoform selectivity in recombinant cells and native tissue. British journal of pharmacology, 166(2), 602-616. https://doi.org/10.1111/j.1476-5381.2011.01782.x