Small-conductance calcium-activated potassium current in normal rabbit cardiac purkinje cells

Thomas A. Reher, Zhuo Wang, Chia Hsiang Hsueh, Po Cheng Chang, Zhenwei Pan, Mohineesh Kumar, Jheel Patel, Jian Tan, Changyu Shen, Zhenhui Chen, Michael C. Fishbein, Michael Rubart, Penelope Boyden, Peng Sheng Chen

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Background-Purkinje cells (PCs) are important in cardiac arrhythmogenesis. Whether small-conductance calcium-activated potassium (SK) channels are present in PCs remains unclear. We tested the hypotheses that subtype 2 SK (SK2) channel proteins and apamin-sensitive SK currents are abundantly present in PCs. Methods and Results-We studied 25 normal rabbit ventricles, including 13 patch-clamp studies, 4 for Western blotting, and 8 for immunohistochemical staining. Transmembrane action potentials were recorded in current-clamp mode using the perforated-patch technique. For PCs, the apamin (100 nmol/L) significantly prolonged action potential duration measured to 80% repolarization by an average of 10.4 ms (95% CI, 0.11-20.72) (n=9, P=0.047). Voltage-clamp study showed that apamin-sensitive SK current density was significantly larger in PCs compared with ventricular myocytes at potentials ≥0 mV. Western blotting of SK2 expression showed that the SK2 protein expression in the midmyocardium was 58% (P=0.028) and the epicardium was 50% (P=0.018) of that in the pseudotendons. Immunostaining of SK2 protein showed that PCs stained stronger than ventricular myocytes. Confocal microscope study showed SK2 protein was distributed to the periphery of the PCs. Conclusions-SK2 proteins are more abundantly present in the PCs than in the ventricular myocytes of normal rabbit ventricles. Apamin-sensitive SK current is important in ventricular repolarization of normal PCs.

Original languageEnglish (US)
Article numbere005471
JournalJournal of the American Heart Association
Volume6
Issue number6
DOIs
StatePublished - Jun 1 2017

Keywords

  • Action potential
  • Apamin
  • Potassium channels
  • Repolarization

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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    Reher, T. A., Wang, Z., Hsueh, C. H., Chang, P. C., Pan, Z., Kumar, M., Patel, J., Tan, J., Shen, C., Chen, Z., Fishbein, M. C., Rubart, M., Boyden, P., & Chen, P. S. (2017). Small-conductance calcium-activated potassium current in normal rabbit cardiac purkinje cells. Journal of the American Heart Association, 6(6), [e005471]. https://doi.org/10.1161/JAHA.117.005471