Exponential fitting of postextrasystolic potentiation may underestimate the cardiac Ca2+ recirculation fraction: A theoretical analysis

Yumiko Doi, Junichi Araki, Waso Fujinaka, Takahiko Kiyooka, Yu Oshima, Gentaro Iribe, Juichiro Shimizu, Kiyoshi Morita, Fumihiko Kajiya, Hiroyuki Suga

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


The recirculation fraction of intramyocardial Ca2+ (RF) has conventionally been obtained from the monotonic decay of postextrasystolic potentiation (PESP). The used assumption is that the decay is exponential. However, we have found that PESP usually decays in alternans even at spontaneous heart rates (>100 beats/min) in excised, cross-circulated canine heart preparations under normal coronary perfusion and normothermia. We have already devised a means of extracting the exponential decay component for RF calculation by subtracting the oscillatory component from the alternans PESP decay by a curve-fitting method. Using mathematics, we assessed the possible error in estimated RF when an exponential curve was naively fit to the alternans PESP decay. We obtained results showing that the exponential assumption may considerably underestimate RF even when the alternans is trivial with the oscillatory component of only 10% of the exponential component.

Original languageEnglish
Pages (from-to)89-96
Number of pages8
JournalJapanese journal of physiology
Issue number2
Publication statusPublished - Apr 2003
Externally publishedYes


  • Arrhythmia
  • Calcium handling
  • Excitation-contraction coupling
  • Heart

ASJC Scopus subject areas

  • Physiology


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