Caffeine-induced current in embryonic heart cells: time course and voltage dependence.
Caffeine-induced current in embryonic heart cells: time course and voltage dependence.
复制标题
胚胎心脏细胞中咖啡因诱导的电流：时间进程和电压依赖性。
DOI：
10.1152/ajpheart.1983.245.3.h528
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
DeHaan,RL
中科院分区：
文献类型：
--
作者：
Clusin,WT;Fischmeister,R;DeHaan,RL
将90- 130微米直径的鸡胚胎心肌细胞聚集体突然暴露于10毫米的咖啡因中，可诱导瞬时内向电流。在目前的研究中，我们在小细胞群（少于10个细胞）中记录了类似的电流，其中咖啡因进入每个细胞的速度很快。由此产生的内向电流由单峰组成，呈指数衰减（主要时间常数为335 +/- 130 ms， -40 mV），峰值振幅高达15.5 microA/cm2。2 μ m d600预处理30 s后，慢向内电流消失，咖啡因诱导的电流持续存在，在快速钠通道完全失活的电位下也能观察到。咖啡因反应的电流-电压关系在-110和-40 mV之间呈线性关系，外推电压截距为+12 mV。然而，向内电流并没有随着进一步去极化而减少或逆转。电位高达+60 mV时，出现了大量内向电流，这比河豚毒素敏感内向电流的反转电位更正。我们得出结论，咖啡因诱导的电流部分是由电致Na+-Ca2+交换介导的。
Abrupt exposure of 90- to 130-micron diameter chick embryonic myocardial cell aggregates to 10 mM caffeine has been shown to induce a transient inward current. In the present study, we recorded a similar current in small cell clusters (less than 10 cells) in which access of caffeine to each of the cells was rapid. The resulting inward current consisted of a single peak, which decayed exponentially (predominant time constant 335 +/- 130 ms at -40 mV) and had a peak amplitude of up to 15.5 microA/cm2. The caffeine-induced current persisted when the slow inward current was abolished by a 30-s pretreatment with 2 microM D 600 and could be observed at potentials where the fast sodium channels were fully inactivated. The current-voltage relation of the caffeine response was linear between -110 and -40 mV, giving an extrapolated voltage intercept of +12 mV. However, the inward current did not diminish or reverse with further depolarization. A substantial inward current occurred at potentials up to +60 mV, which is more positive than the reversal potential of the tetrodotoxin-sensitive inward current. We conclude that the caffeine-induced current is mediated in part by electrogenic Na+-Ca2+ exchange.