CCDI: A new ligand that modulates mammalian type 1 ryanodine receptor (RyR1)

Chengju Tian, Chun Hong Shao, Christina Padanilam, Edward Ezell, Jaipaul Singh, Shelby Kutty, Keshore R. Bidasee

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Background and Purpose Ryanodine receptors (RyRs) are Ca 2+-release channels on the sarco(endo)plasmic reticulum that modulate a wide array of physiological functions. Three RyR isoforms are present in cells: RyR1, RyR2 and RyR3. To date, there are no reports on ligands that modulate RyR in an isoform-selective manner. Such ligands are not only valuable research tools, but could serve as intermediates for development of therapeutics. Experimental approach Pyrrole-2-carboxylic acid and 1,3-dicyclohexylcarbodiimide were allowed to react in carbon tetrachloride for 24-h at low temperatures and pressures. The chemical structures of the two products isolated were elucidated using NMR spectrometry, mass spectrometry and elemental analyses. [3H]-ryanodine binding, lipid bilayer and time-lapsed confocal imaging were used to determine their effects on RyR isoforms. Key results The major product, 2-cyclohexyl-3-cyclohexylimino-2, 3, dihydro-pyrrolo[1,2-c]imidazol-1-one (CCDI) dose-dependently potentiated Ca 2+-dependent binding of [3H]-ryanodine to RyR1, with no significant effects on [3H]-ryanodine binding to RyR2 or RyR3. CCDI also reversibly increased the open probability (Po) of RyR1 with minimal effects on RyR2 and RyR3. CCDI induced Ca2+ transients in C2C12 skeletal myotubes, but not in rat ventricular myocytes. This effect was blocked by pretreating cells with ryanodine. The minor product 2-cyclohexyl-pyrrolo[1,2-c]imidazole-1,3-dione had no effect on either [ 3H]-ryanodine binding or Po of RyR1, RyR2 and RyR3. Conclusions and implications A new ligand that preferentially modulates RyR1 was identified. In addition to being an important research tool, the pharmacophore of this small molecule could serve as a template for the synthesis of other isoform-selective modulators of RyRs.

Original languageEnglish (US)
Pages (from-to)4097-4111
Number of pages15
JournalBritish Journal of Pharmacology
Issue number17
StatePublished - Sep 2014


  • 2-cyclohexyl-3-cyclohexylimino-2,3-dihydro-pyrrolo[1,2-c]imidazol-1-one (CCDI)
  • isoforms-selective
  • ryanodine receptor
  • sarcoplasmic reticulum

ASJC Scopus subject areas

  • Pharmacology


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