Mechanisms for IMPULSE INITIATION IN HUMAN ATRIAL FIBERS
Mechanisms for IMPULSE INITIATION IN HUMAN ATRIAL FIBERS
复制标题
人类心房纤维脉冲启动机制
作者：
L. Mary;A. Hordof;P. Danilo;J. Malm;M. Rosen
我们使用标准的微电极技术来研究心脏手术中获得的台氏灌注的人心房纤维。两种类型的持续节律活动发生。1例由缓慢的4相去极化引起，自发频率= 20-26次/分。肾上腺素增加，慢通道阻滞剂AHR-2666（AHR）和维拉帕米降低4相斜率和自发频率。乙酰胆碱（ACh）和利多卡因使第4相斜率减小，但减慢幅度小于AHR和维拉帕米。河豚毒素（TTX）也降低了第4相的斜率和自发频率，在一定程度上是中间的AHR-维拉帕米和乙酰胆碱-利多卡因的行动。第二种类型的持续节律活动是由延迟后除极（DAD）触发的。DAD振幅随刺激周期长度的减少而增加，在临界周期长度，DAD以> 70次/min的速率启动自发动作电位序列。自发发生的DAD被AHR抑制，ACh短暂减少。ACh的这种作用伴随着纤维的超极化。肾上腺素也可诱发DAD。这些DAD不受TTX，利多卡因或ACh的影响，并被AHR和维拉帕米抑制。总之，缓慢的内向电流有助于人类心房的自律性或DAD的持续节律性活动。TTX敏感电流也有助于自动性。自发发生的DAD在很大程度上对增加K电导的药物的作用不敏感（尽管ACh具有瞬时作用），而在肾上腺素存在下诱导的DAD对增加K电导的药物（ACh，利多卡因）或TTX无反应。Circ Res 47：267-277，1980
We used standard microelectrode techniques to study Tyrode's-superfused human atrial fibers obtained at cardiac surgery. Two types of sustained rhythmic activity occurred. One resulted from slow phase 4 depolarization and had a spontaneous rate = 20-26 beats/min. Epinephrine increased and the slow channel blockers, AHR-2666 (AHR) and verapamil decreased both phase 4 slope and spontaneous rate. Acetylcholine (ACh) and lidocaine decreased the slope of phase 4, but the slowing of rate was less than that induced by AHR and verapamil. Tetrodotoxin (TTX) also decreased the slope of phase 4 and spontaneous rate, to an extent that was intermediate between the actions of AHR-verapamil and ACh-lidocaine. A second type of sustained rhythmic activity was triggered by delayed afterdepolarizations (DAD). DAD amplitude increased as stimulus cycle length decreased and, at critical cycle lengths, DAD initiated trains of spontaneous action potentials at rates > 70 beats/min. Spontaneously occurring DAD were suppressed by AHR and were transiently diminished by ACh. This effect of ACh was accompanied by hyperpolarization of the fibers. DAD also were induced by epineph-rine. These DAD were unaffected by TTX, lidocaine, or ACh and were suppressed by AHR and verapamil. In summary, the slow inward current contributes to the sustained rhythmic activity that occurs with automaticity or DAD in human atrium. A TTX-sensitive current also contributes to automaticity. DAD that occur spontaneously are largely insensitive to the effects of agents that increase K conductance (although ACh has a transient effect) and those that are induced in the presence of epinephrine do not respond to agents which increase K conductance (ACh, lidocaine) or TTX. Circ Res 47: 267-277, 1980
电压钳制心脏浦肯野纤维中的细胞内 [Ca2] 瞬变。
DOI：
10.1007/bf00584312
发表时间：
1982
期刊：
Pflugers Archiv : European journal of physiology
影响因子：
--
作者：
Wier,WG;Isenberg,G
通讯作者：
Isenberg,G