Aging and digitalis sensitivity of cardiac muscle in rats.
Aging and digitalis sensitivity of cardiac muscle in rats.
复制标题
大鼠心肌的衰老和洋地黄敏感性。
DOI：
10.1016/0014-2999(85)90733-2
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发表时间：
1985
影响因子：
5
通讯作者：
Akera,T
中科院分区：
文献类型：
--
作者：
Katano,Y;Kennedy,RH;Stemmer,PM;Temma,K;Akera,T
在从3、8或26月龄Fischer 344大鼠获得的左心房和左心室肌制备物中研究了老年大鼠对哇巴因致心律失常作用的耐受性降低的原因。在1.5Hz电刺激下，哇巴因正性肌力作用的浓度-反应曲线随年龄增长有左移的趋势。毒性作用发生在较低的哇巴因或地高辛浓度在心室肌中获得的衰老大鼠，特别是当肌肉刺激在较高的频率（4 Hz），虽然在耐受性的哇巴因的毒性作用的差异是不明显的心房肌制剂刺激在1.5 Hz。在以1.5 Hz起搏的灌注心室肌制备物中，未观察到细胞内钠或钾浓度的年龄相关差异。Na+诱导的Na+，K+-ATP酶活性无明显的年龄效应。然而，在老年心肌，特别是在高频刺激下，动作电位的上行速度降低，并且跟随高频刺激的能力受到损害。这些结果表明，老年心室肌钠泵的储备能力降低，从而提高其对强心苷的敏感性。
The cause of the reduced tolerance of aged rats to the arrhythmogenic effect of ouabain was studied in left atrial and left ventricular muscle preparations obtained from 3-, 8- or 26-month old Fischer 344 rats. Under 1.5-Hz stimulation, the concentration-response curves for the positive inotropic effect of ouabain showed a tendency to shift to the left with age. The toxic effects occured at lower ouabain or digoxin concentrations in the ventricular muscle obtained from senescent rats especially when the muscle was stimulated at a higher frequency (4 Hz), although differences in tolerance to the toxic effect of ouabain were not apparent in atrial muscle preparations stimulated at 1.5 Hz. No age-related difference in intracellular sodium or potassium concentration was observed in perfused ventricular muscle preparations paced at 1.5 Hz. There was no significant age effect on Na+-induced activation of Na+,K+-ATPase. In aged myocardium, however, the upstroke velocity of the action potential was reduced especially under high frequency stimulations, and the ability to follow high frequency stimulation was compromised. These results suggest that reserve capacity of the sodium pump is reduced in aged ventricular muscle, thereby elevating its sensitivity to the cardiac glycoside.