Roles of impaired intracellular calcium cycling in arrhythmogenicity of diabetic mouse model

Chung Chuan Chou, Chien Te Ho, Hui Ling Lee, Yen Chu, Tzung Hai Yen, Ming Shien Wen, Shien-Fong Lin, Cheng Hung Lee, Po Cheng Chang*

*Corresponding author for this work

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Background: Diabetes mellitus is associated an increased risk of ventricular arrhythmias (VAs), but the underlying electrophysiological mechanisms are not fully explored. This study was aimed to test whether dynamic factors and Cai handling play roles in arrhythmogenesis of a diabetic animal model. Methods: We used 26 db/db type 2 diabetes mice and 28 control mice in this study. VA inducibility was evaluated in vivo under isoflurane general anesthesia. The intracellular Ca2+ (Cai) and membrane voltage (Vm) signals of the Langendorff-perfused mouse hearts were simultaneously recorded using the optical mapping technique. Action potential duration (APD), Cai dynamics conduction velocity (CV), and arrhythmogenic alternans were analyzed. Western blot was conducted to examine expressions of calcium handling and associated ion channels proteins. Results: The diabetic db/db mice showed significantly increased VA inducibility and severity. Longer APD and Cai transient duration and slower Cai decay and CV in the db/db mice than these in the control ones were observed. Dynamic pacing showed increased incidence of spatially discordant alternans leading to more VA inducibility in the db/db mice. Western blot analyses revealed increased phosphorylated-Ca2+/calmodulin-dependent protein kinase II protein expression and decreased ryanodine receptor protein expression, which probably underlay the molecular mechanisms of enhanced arrhythmogenicity in db/db mice. Conclusions: The type 2 diabetic mouse hearts show impaired repolarization, Cai handling homeostasis, and cardiac conduction reserve, leading to vulnerability of spatially discordant alternans development and induction of VA. Altered Cai-handling protein expressions probably underlie the molecular mechanisms of arrhythmogenicity in the type 2 diabetes animal model.

Original languageEnglish
Pages (from-to)1087-1095
Number of pages9
JournalPACE - Pacing and Clinical Electrophysiology
Volume40
Issue number10
DOIs
StatePublished - 1 Oct 2017

Keywords

  • arrhythmia
  • conduction velocity
  • db/db mouse
  • intracellular calcium dynamics
  • type 2 diabetes

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    Chou, C. C., Ho, C. T., Lee, H. L., Chu, Y., Yen, T. H., Wen, M. S., Lin, S-F., Lee, C. H., & Chang, P. C. (2017). Roles of impaired intracellular calcium cycling in arrhythmogenicity of diabetic mouse model. PACE - Pacing and Clinical Electrophysiology, 40(10), 1087-1095. https://doi.org/10.1111/pace.13166