Doi Yumiko, Araki Junichi, Fujinaka Waso, Kiyooka Takahiko, Oshima Yu, Iribe Gentaro, Shimizu Juichiro, Morita Kiyoshi, Kajiya Fumihiko, Suga Hiroyuki
Department of Anesthesiology and Resuscitology, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama, 700-8558, Japan.
Jpn J Physiol. 2003 Apr;53(2):89-96. doi: 10.2170/jjphysiol.53.89.
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.
心肌内钙离子的再循环分数（RF）传统上是通过期外收缩后增强（PESP）的单调衰减来获得的。所采用的假设是衰减呈指数形式。然而，我们发现，即使在正常冠状动脉灌注和正常体温下，在离体交叉循环犬心制备中，即使在自发心率（>100次/分钟）时，PESP通常也会以交替变化的形式衰减。我们已经设计出一种方法，通过曲线拟合从交替变化的PESP衰减中减去振荡成分来提取用于RF计算的指数衰减成分。我们用数学方法评估了在将指数曲线简单拟合到交替变化的PESP衰减时，估计RF中可能存在的误差。我们得到的结果表明，即使交替变化很微小，振荡成分仅为指数成分的10%，指数假设也可能会严重低估RF。
