Chopra M, Singh S
Department of Biochemical Pharmacology, State University of New York at Buffalo 14260.
J Neurobiol. 1994 Feb;25(2):119-26. doi: 10.1002/neu.480250204.
Ionic currents are regulated by many conditions including disease states, aging, learning and memory, and chronic drug treatment. Here we describe a novel phenomenon of regulation of ionic currents by developmental temperature. Raising Drosophila larvae at 28 degrees C instead of 18 degrees C increased one of the two voltage-activated K(+)-currents, the delayed sustained IK, in their muscles by up to 3.5-fold, with little effect on the early transient current, IA. Consistent with this increase in IK, the amplitude and the duration of the action potentials were reduced. The major increase in IK occurred between a rather abrupt interval from 25 degrees to 28 degrees C. The activation curve of the increased current was shifted towards hyperpolarizing potentials. There was no change in activation kinetics. This phenomenon has mechanistic implications for activity-dependent neuronal plasticity, expression of ion channels in cultured cells and heterologous systems, phototransduction, and behavior. The specificity of the regulation suggests a discrete mechanism geared to affect excitability such that it can respond to altered external stimuli such as temperature.
离子电流受多种条件调节，包括疾病状态、衰老、学习与记忆以及长期药物治疗。在此，我们描述了发育温度对离子电流调节的一种新现象。将果蝇幼虫饲养在28摄氏度而非18摄氏度环境下，会使它们肌肉中两种电压激活钾电流之一、延迟持续的IK电流增加多达3.5倍，而对早期瞬时电流IA影响很小。与IK电流的这种增加相一致，动作电位的幅度和持续时间会减小。IK电流的主要增加发生在25摄氏度到28摄氏度这一相当突然的区间内。增加电流的激活曲线向超极化电位方向移动。激活动力学没有变化。这种现象对活动依赖性神经元可塑性、培养细胞和异源系统中离子通道的表达、光转导及行为具有机制方面的意义。这种调节的特异性表明存在一种专门影响兴奋性的离散机制，使其能够对诸如温度等改变的外部刺激做出反应。
