Open AccessReduction in Kv Current Enhances the Temporal Dispersion of the Action Potential in Diabetic Myocytes: Insights From a Novel Repolarization Algorithm
Author(s) -
Meo Marianna,
Meste Olivier,
Signore Sergio,
Sorrentino Andrea,
Cannata Antonio,
Zhou Yu,
Matsuda Alex,
Luciani Marco,
Kannappan Ramaswamy,
Goichberg Polina,
Leri Annarosa,
Anversa Piero,
Rota Marcello
Publication year - 2016
Publication title -
journal of the american heart association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.494
H-Index - 85
ISSN - 2047-9980
DOI - 10.1161/jaha.115.003078
Subject(s) - repolarization , medicine , myocyte , qt interval , diabetes mellitus , cardiology , ventricular action potential , endocrinology , in vivo , patch clamp , electrophysiology , biology , microbiology and biotechnology
Background Diabetes is associated with prolongation of the QT interval of the electrocardiogram and enhanced dispersion of ventricular repolarization, factors that, together with atherosclerosis and myocardial ischemia, may promote the occurrence of electrical disorders. Thus, we tested the possibility that alterations in transmembrane ionic currents reduce the repolarization reserve of myocytes, leading to action potential ( AP ) prolongation and enhanced beat‐to‐beat variability of repolarization. Methods and Results Diabetes was induced in mice with streptozotocin ( STZ ), and effects of hyperglycemia on electrical properties of whole heart and myocytes were studied with respect to an untreated control group (Ctrl) using electrocardiographic recordings in vivo, ex vivo perfused hearts, and single‐cell patch‐clamp analysis. Additionally, a newly developed algorithm was introduced to obtain detailed information of the impact of high glucose on AP profile. Compared to Ctrl, hyperglycemia in STZ ‐treated animals was coupled with prolongation of the QT interval, enhanced temporal dispersion of electrical recovery, and susceptibility to ventricular arrhythmias, defects observed, in part, in the Akita mutant mouse model of type I diabetes. AP was prolonged and beat‐to‐beat variability of repolarization was enhanced in diabetic myocytes, with respect to Ctrl cells. Density of Kv K + and L‐type Ca 2+ currents were decreased in STZ myocytes, in comparison to cells from normoglycemic mice. Pharmacological reduction of Kv currents in Ctrl cells lengthened AP duration and increased temporal dispersion of repolarization, reiterating features identified in diabetic myocytes. Conclusions Reductions in the repolarizing K + currents may contribute to electrical disturbances of the diabetic heart.