The calcium and voltage clocks in sinoatrial node automaticity

Boyoung Joung, Masahiro Ogawa, Shien Fong Lin, Peng Sheng Chen

Research output: Contribution to journalReview article

15 Citations (Scopus)

Abstract

Recent evidence indicates that the voltage (cyclic activation and deactivation of membrane ion channels) and Ca2+ clocks (rhythmic spontaneous sarcoplasmic reticulum Ca2+ release) jointly regulate sinoatrial node (SAN) automaticity. Since the intact SAN is a heterogeneous structure that includes multiple different cell types interacting with each other, the relative importance of the voltage and Ca2+ clocks for pacemaking may be variable in different regions of the SAN. Recently, we performed optical mapping in isolated and Langendorff-perfused canine right atria. We mapped the intracellular calcium (Cai) and membrane potentials of the intact SAN simultaneously. Using previously described criteria of the timing of the late diastolic Cai elevation (LDCAE) relative to the action potential upstroke to detect Ca2+ clock activity, we demonstrated that the sinus rate increased and the leading pacemaker shifted to the superior SAN with the robust LDCAE during β-adrenergic stimulation. We also showed that the LDCAE was caused by spontaneous diastolic SR Ca 2+ release and was closely related with heart rate changes. We conclude that the Ca and voltage clocks work synergistically to generate SAN automaticity.

Original languageEnglish
Pages (from-to)217-222
Number of pages6
JournalKorean Circulation Journal
Volume39
Issue number6
DOIs
Publication statusPublished - 2009 Jun

All Science Journal Classification (ASJC) codes

  • Internal Medicine
  • Cardiology and Cardiovascular Medicine

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