Delayed after depolarization-mediated triggered activity associated with slow calcium sequestration near the endocardium.
Delayed after depolarization-mediated triggered activity associated with slow calcium sequestration near the endocardium.
复制标题
去极化介导的触发活动后延迟，该活动与心内膜附近缓慢的钙隔离相关。
DOI：
10.1046/j.1540-8167.2005.40429.x
复制
发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Katra,RodolpheP
中科院分区：
文献类型：
--
作者：
Laurita,KennethR;Katra,RodolpheP
Introduction:Previously, we have shown that cells near the endocardium are more prone to elevated diastolic intracellular calcium levels than cells near the epicardium. The arrhythmogenic consequence of such regional differences in calcium handling is not clear.Methods and Results:Using optical mapping techniques, calcium transients and action potentials were recorded simultaneously from ventricular sites across the transmural wall of the arterially perfused canine left ventricular wedge preparation during control conditions, and under conditions of increased calcium entry (IKblockade and β‐adrenergic stimulation). Under conditions of enhanced calcium entry, the decay of the calcium transient and diastolic calcium levels during rapid pacing were slower (38%, P < 0.01) and higher (215%, P < 0.02), respectively, near (within ∼3 mm) the endocardium compared to the epicardium (n = 9). Immediately after termination of rapid pacing under conditions of increased calcium entry, ectopic activity and simultaneous delayed afterdepolarizations and spontaneous calcium release events were observed. Over all experiments, ectopic activity occurred more frequently closer to the endocardium compared to the epicardium.Conclusions:Under conditions of enhanced calcium entry, myocytes closer to the endocardium exhibit a higher level of diastolic calcium and greater ectopic activity compared to the epicardium. We show for the first time simultaneous delayed afterdepolarization and spontaneous calcium release events from myocytes in a normally coupled multicellular preparation. These data combined suggest that myocytes near the endocardium are more susceptible to calcium‐mediated triggered activity.
