title: Exponential fitting of postextrasystolic potentiation may underestimate the cardiac Ca2+ recirculation fraction: a theoretical analysis.
abstract: The recirculation fraction of intramyocardial Ca(2+) (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.
authors.affiliation: Department of Anesthesiology and Resuscitology, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama, 700-8558, Japan. yumdoi@yahoo.co.jp
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Doi
authors.forename: Junichi
authors.initials: J
authors.lastname: Araki
authors.forename: Waso
authors.initials: W
authors.lastname: Fujinaka
authors.forename: Takahiko
authors.initials: T
authors.lastname: Kiyooka
authors.forename: Yu
authors.initials: Y
authors.lastname: Oshima
authors.forename: Gentaro
authors.initials: G
authors.lastname: Iribe
authors.forename: Juichiro
authors.initials: J
authors.lastname: Shimizu
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Morita
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Kajiya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suga
mesh_terms: D000465:Algorithms; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D005117:Cardiac Complexes, Premature / Q000503:physiopathology*; D004285:Dogs; D001330:Electronic Data Processing; D006321:Heart / Q000502:physiology* / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000502:physiology; D012107:Research Design; D012519:Sarcoplasmic Reticulum / Q000502:physiology; D013599:Systole / Q000502:physiology
chemical_list: D002118:Calcium