ADRENERGIC MODULATION OF THE DELAYED RECTIFIER POTASSIUM CHANNEL IN CALF CARDIAC PURKINJE-FIBERS
ADRENERGIC MODULATION OF THE DELAYED RECTIFIER POTASSIUM CHANNEL IN CALF CARDIAC PURKINJE-FIBERS
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DOI：
10.1016/s0006-3495(86)83713-4
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发表时间：
1986-04-01
影响因子：
3.4
通讯作者：
KASS, RS
中科院分区：
文献类型：
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作者：
BENNETT, P;MCKINNEY, L;KASS, RS
我们研究了神经激素去甲肾上腺素对小牛心脏浦肯野纤维延迟整流钾通道的调节。我们发现0.5 μ M去甲肾上腺素使该K通道电流增加2.7倍。对于1 μ M和更高的浓度，发现最大增加约4。去甲肾上腺素使K通道逆转电位向更负的值产生小的（< 5 mV）和可变的偏移。钾通道的动力学是很好地描述了一个双指数过程，无论是在存在和不存在去甲肾上腺素。然而，去甲肾上腺素实质上降低了较慢的时间常数，而对快时间常数没有显著影响。除大正电位外，存在去甲肾上腺素时的钾通道激活曲线与对照曲线非常相似。一个简单的顺序三态模型，该通道可以重现这些数据都有和没有去甲肾上腺素。从这个模型推导出的速率常数的多项式是电压的二次函数，表明电场诱导的偶极子参与该通道的门控。去甲肾上腺素的大多数动力学效应似乎是在一个单一的速率常数。
We have investigated the modulation of the delayed rectifier potassium channel in calf cardiac Purkinje fibers by the neurohormone norepinephrine. We find that 0.5 .mu.M norepinephrine increases this K channel current by a factor of 2.7. A maximal increase of about four was found for concentrations of 1 .mu.M and above. Norepinephrine produced a small (< 5 mV) and variable shift of the K channel reversal potential toward more negative values. The kinetics of the potassium channel are well described by a two-exponential process, both in the absence and presence of norepinephrine. However, norepinephrine substantially decreases the slower time constant with no significant effect on the fast time constant. Potassium channel activation curves in the presence of norepinephrine are very similar to control curves except at large positive potentials. A simple sequential three-state model for this channel can reproduce these data both with and without norepinephrine. The logarithms of the rate constants derived from this model are quadratic functions of voltage, suggesting the involvement of electric field-induced dipoles in the gating of this channel. Most of the kinetic effects of norepinephrine appear to be on a single rate constant.