Escande D, Loisance D, Planche C, Coraboeuf E
Am J Physiol. 1985 Oct;249(4 Pt 2):H843-50. doi: 10.1152/ajpheart.1985.249.4.H843.
Because the frequency of atrial arrhythmia increases dramatically with age in humans, we investigated age-related changes of cellular electrical activity in human atrial fibers, utilizing standard microelectrode techniques. Twenty-four atrial samples, uniformly exhibiting fast responses, were selected. Patients were in two different age groups: 10.0 +/- 7.0 mo and 54.4 +/- 9.7 yr. Although mean maximum diastolic electrical potential did not significantly differ, the two groups showed marked dissimilarities in action potential (AP) shape. Adult-type APs always exhibited an initial notch followed by a low-level prolonged plateau, whereas APs of the young were more triangular and had a short plateau approaching zero potential. 4-Aminopyridine (0.5 mM) markedly increased the level of the adult AP plateau without suppressing the initial notch, which disappeared after further addition of caffeine (10 mM). The simultaneous action of the two drugs changed an adult-type AP into a young type. The drug effects were much less marked in young atria. Our results suggest that an age-related increase in transient outward currents can account for the differences in plateau shape described. Moreover, age-related differences in plateau configuration in response to a period of rest suggest a faster repriming kinetic of these currents in adults.
由于人类心房心律失常的发生率随年龄增长而显著增加，我们利用标准微电极技术研究了人类心房纤维细胞电活动的年龄相关变化。选取了24个均表现出快速反应的心房样本。患者分为两个不同年龄组：10.0±7.0个月和54.4±9.7岁。尽管平均最大舒张电位无显著差异，但两组在动作电位（AP）形态上表现出明显不同。成人型动作电位总是先出现一个初始切迹，随后是一个低水平的延长平台期，而年轻人的动作电位更呈三角形，且有一个接近零电位的短平台期。4-氨基吡啶（0.5 mM）显著提高了成人动作电位平台期的水平，且未抑制初始切迹，在进一步加入咖啡因（10 mM）后切迹消失。两种药物同时作用将成人型动作电位转变为年轻型。药物作用在年轻心房中不太明显。我们的结果表明，与年龄相关的瞬时外向电流增加可以解释所描述的平台期形态差异。此外，在休息一段时间后，平台期构型的年龄相关差异表明成人中这些电流的再激发动力学更快。
