Calcium dynamics and the mechanisms of atrioventricular junctional rhythm

Daehyeok Kim, Tetsuji Shinohara, Boyoung Joung, Mitsunori Maruyama, Eue Keun Choi, Young Keun On, Seongwook Han, Michael C. Fishbein, Shien Fong Lin, Peng Sheng Chen

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Objectives: The purpose of this study was to test the hypothesis that rhythmic spontaneous sarcoplasmic reticulum calcium (Ca) release (the "Ca clock") plays an important role in atrioventricular junction (AVJ) automaticity. Background: The AVJ is a primary backup pacemaker to the sinoatrial node. The mechanisms of acceleration of AVJ intrinsic rate during sympathetic stimulation are unclear. Methods: We simultaneously mapped transmembrane potential and intracellular Ca in Langendorff-perfused canine AVJ preparations that did not contain sinoatrial node (n = 10). Results: Baseline AVJ rate was 37.5 ± 4.0 beats/min. The wavefront from leading pacemaker site propagated first through the slow pathway, then the fast pathway and atria. There was no late diastolic Ca elevation (LDCAE) at baseline. Isoproterenol up to 3 μmol/l increased heart rate to 100 ± 6.8 beats/min, concomitant with the appearance of LDCAE that preceded the phase 0 of action potential by 97.3 ± 35.2 ms and preceded the onset of late diastolic depolarization by 23.5 ± 3.5 ms. Caffeine also produced LDCAE and AVJ acceleration. The maximal slope of LDCAE and diastolic depolarization always colocalized with the leading pacemaker sites. Ryanodine markedly slowed the rate of spontaneous AVJ rhythm. Isoproterenol did not induce LDCAE in the presence of ryanodine. The If blocker ZD 7288 did not prevent LDCAE or AVJ acceleration induced by isoproterenol (n = 2). Conclusions: Isoproterenol and caffeine induced LDCAE and accelerated intrinsic AVJ rhythm. Consistent colocalization of the maximum LDCAE and the leading pacemaker sites indicates that the Ca clock is important to the intrinsic AVJ rate acceleration during sympathetic stimulation.

Original languageEnglish (US)
Pages (from-to)805-812
Number of pages8
JournalJournal of the American College of Cardiology
Volume56
Issue number10
DOIs
StatePublished - Aug 31 2010

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Isoproterenol
Calcium
Ryanodine
Sinoatrial Node
Caffeine
Sarcoplasmic Reticulum
Membrane Potentials
Action Potentials
Canidae
Heart Rate

Keywords

  • arrhythmia
  • automaticity
  • electrophysiology
  • optical mapping
  • sympathetic stimulation

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

Cite this

Calcium dynamics and the mechanisms of atrioventricular junctional rhythm. / Kim, Daehyeok; Shinohara, Tetsuji; Joung, Boyoung; Maruyama, Mitsunori; Choi, Eue Keun; On, Young Keun; Han, Seongwook; Fishbein, Michael C.; Lin, Shien Fong; Chen, Peng Sheng.

In: Journal of the American College of Cardiology, Vol. 56, No. 10, 31.08.2010, p. 805-812.

Research output: Contribution to journalArticle

Kim, D, Shinohara, T, Joung, B, Maruyama, M, Choi, EK, On, YK, Han, S, Fishbein, MC, Lin, SF & Chen, PS 2010, 'Calcium dynamics and the mechanisms of atrioventricular junctional rhythm', Journal of the American College of Cardiology, vol. 56, no. 10, pp. 805-812. https://doi.org/10.1016/j.jacc.2010.03.070
Kim, Daehyeok ; Shinohara, Tetsuji ; Joung, Boyoung ; Maruyama, Mitsunori ; Choi, Eue Keun ; On, Young Keun ; Han, Seongwook ; Fishbein, Michael C. ; Lin, Shien Fong ; Chen, Peng Sheng. / Calcium dynamics and the mechanisms of atrioventricular junctional rhythm. In: Journal of the American College of Cardiology. 2010 ; Vol. 56, No. 10. pp. 805-812.
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AU - Shinohara, Tetsuji

AU - Joung, Boyoung

AU - Maruyama, Mitsunori

AU - Choi, Eue Keun

AU - On, Young Keun

AU - Han, Seongwook

AU - Fishbein, Michael C.

AU - Lin, Shien Fong

AU - Chen, Peng Sheng

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