Inositol 1, 4, 5-trisphosphate receptors and human left ventricular myocytes

Sergio Signore, Andrea Sorrentino, João Ferreira-Martins, Ramaswamy Kannappan, Mehrdad Shafaie, Fabio Del Ben, Kazuya Isobe, Christian Arranto, Ewa Wybieralska, Andrew Webster, Fumihiro Sanada, Barbara Ogórek, Hanqiao Zheng, Xiaoxia Liu, Federica Del Monte, David A. D'Alessandro, Oriyanhan Wunimenghe, Robert E. Michler, Toru Hosoda, Polina GoichbergAnnarosa Leri, Jan Kajstura, Piero Anversa, Marcello Rota

Research output: Contribution to journalArticlepeer-review


BACKGROUND-: Little is known about the function of inositol 1,4,5-trisphosphate receptors (IP3Rs) in the adult heart experimentally. Moreover, whether these Ca release channels are present and play a critical role in human cardiomyocytes remains to be defined. IP3Rs may be activated after Gαq-protein-coupled receptor stimulation, affecting Ca cycling, enhancing myocyte performance, and potentially favoring an increase in the incidence of arrhythmias. METHODS AND RESULTS-: IP3R function was determined in human left ventricular myocytes, and this analysis was integrated with assays in mouse myocytes to identify the mechanisms by which IP3Rs influence the electric and mechanical properties of the myocardium. We report that IP3Rs are expressed and operative in human left ventricular myocytes. After Gαq-protein-coupled receptor activation, Ca mobilized from the sarcoplasmic reticulum via IP3Rs contributes to the decrease in resting membrane potential, prolongation of the action potential, and occurrence of early afterdepolarizations. Ca transient amplitude and cell shortening are enhanced, and extrasystolic and dysregulated Ca elevations and contractions become apparent. These alterations in the electromechanical behavior of human cardiomyocytes are coupled with increased isometric twitch of the myocardium and arrhythmic events, suggesting that Gαq-protein-coupled receptor activation provides inotropic reserve, which is hampered by electric instability and contractile abnormalities. Additionally, our findings support the notion that increases in Ca load by IP3Rs promote Ca extrusion by forward-mode Na/Ca exchange, an important mechanism of arrhythmic events. CONCLUSIONS-: The Gαq-protein/coupled receptor/IP3R axis modulates the electromechanical properties of the human myocardium and its propensity to develop arrhythmias.

Original languageEnglish
Pages (from-to)1286-1297
Number of pages12
Issue number12
Publication statusPublished - Sep 17 2013


  • arrhythmias
  • calcium
  • cardiac
  • inositol 1,4,5-trisphosphate receptors
  • myocytes, cardiac

ASJC Scopus subject areas

  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine


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