MECHANICALLY INDUCED ACTION-POTENTIAL CHANGES AND ARRHYTHMIA IN ISOLATED AND INSITU CANINE HEARTS
MECHANICALLY INDUCED ACTION-POTENTIAL CHANGES AND ARRHYTHMIA IN ISOLATED AND INSITU CANINE HEARTS
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DOI：
10.1093/cvr/23.3.213
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发表时间：
1989-03-01
影响因子：
10.8
通讯作者：
SAGAWA, K
中科院分区：
文献类型：
--
作者：
FRANZ, MR;BURKHOFF, D;SAGAWA, K
离体心肌组织的牵拉引起跨膜动作电位的电生理和潜在的致心律失常变化，但缺乏完整哺乳动物心脏的相应数据。因此，在离体、交叉循环和原位犬心脏中研究了心室容积和压力增加对心外膜单相动作电位的影响。在7个离体心脏中，心室容积和压力的增加导致（1）动作电位振幅的线性相关降低（r = 0.988;斜率= 0.41%振幅）。ml ~（-1）;体积截距= 17.6 ml），主要是由于最大舒张电位降低;（2）肌动蛋白电位平台期（20%复极化时）降低19（SD 8）%;（3）出现早期后去极化，达到总动作电位振幅的18%。后除极仅发生在心室流出道在舒张末期受阻时，而不发生在收缩末期。在8个原位心脏中，升主动脉短暂闭塞引起的左心室内压增加也伴随着最大舒张电位和动作电位平台持续时间的降低，以及早期后除极的出现。在离体和在体完整心室中，负荷引起的电生理变化与室性早搏的发生有关。这些数据表明，机械过载产生显着的电生理变化，在完整的犬心室，这可能会导致心律失常。
Stretch of excised myocardial tissue causes electrophysiological and potentially arrhythmogenic changes in transmembrane action potentials but corresponding data of the intact mammalian heart are lacking. The effects of increases in ventricular volume and pressure on epicardial monophasic action potentials were therefore investigated in isolated, cross circulated and in situ canine hearts. In seven isolated hearts, increases in ventricular volume and pressure resulted in (1) a linearly related decrease in action potential amplitude (r = 0.988; slope = 0.41% amplitude .cntdot. ml-1; volume intercept = 17.6 ml), mainly due to a decrease in maximum diastolic potential; (2) a decrease in actin potential plateau duration (at 20% repolarization) by 19 (SD 8)%; and (3) appearance of early afterdepolarisations, reaching up to 18% of total action potential amplitude. Afterdepolarisations occurred only when ventricular outflow was obstructed at end diastole but not at end systole. In eight in situ hearts, increase in left intraventricular pressure produced by transient occlusions of the ascending aorta was also accompanied by decrease in maximum diastolic potential and action potential plateau duration, and by appearance of early afterdepolarisations. In both isolated and in situ intact ventricles, the loading induced electrophysiological changes were associated with occurrence of ectopic ventricular beats. These data show that mechanical overload produces significant electrophysiological changes in the intact canine ventricle which may lead to arrhythmia.