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首页> 外文期刊>The European Journal of Neuroscience >Modulation of Ca2+ currents in rat thalamocortical relay neurons by activity and phosphorylation.
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Modulation of Ca2+ currents in rat thalamocortical relay neurons by activity and phosphorylation.

机译：通过活动和磷酸化对大鼠丘脑皮质中枢神经元中Ca2 +电流的调节。

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摘要

Rhythmic low and high frequency activity in thalamocortical networks depend critically on activation of low- and high-voltage-activated (LVA, HVA) Ca2+ currents. In order to test whether Ca2+ currents are modified during repetitive activation, acutely isolated thalamocortical relay neurons of rats, at postnatal days 12 (P12) to P20, were investigated using patch-clamp, Ca2+ imaging and Western blot techniques. High-voltage-activated, but not LVA Ca2+ currents were reduced significantly during 2 Hz stimulation. Ca2+ imaging experiments demonstrated a close correlation between the increase in intracellular Ca2+ levels and the decrease in HVA Ca2+ current amplitudes. Further examination of HVA Ca2+ currents revealed a 'U-shaped' inactivation curve and a time-dependent inactivation process that could be described by a two-exponential function. The 'U-shape' was significantly reduced, current amplitude was increased significantly and time-dependent inactivation revealed a one-exponential decline with Ba2+ as the charge carrier, following activation of the cAMP/PKA pathway, and following application of phosphatase inhibitors (ascomycin, calyculin A). Western blot analysis and the effect of ascomycin indicated an involvement of calcineurin in the inactivation process. Isolation of HVA Ca2+ current components by subtype-specific blockers revealed that changes in time-dependent inactivation, inactivation curve and current amplitude were carried mainly by L-type and N-type Ca2+ currents. Furthermore, Ca2+-dependent inactivation was operative during stimulation protocols mimicking tonic action potential firing. These data indicate a modulation of L- and N-type Ca2+ channels by phosphorylation, resulting jointly in an increased intracellular Ca2+ influx during activity of the ascending brainstem system, the latter occurring during states of wakefulness.
机译：丘脑皮层网络中的有节奏的低频和高频活动主要取决于低压和高压激活（LVA，HVA）Ca2 +电流的激活。为了测试在重复激活过程中是否改变了Ca2 +电流，使用膜片钳，Ca2 +成像和Western blot技术研究了大鼠出生后第12天（P12）至P20的急性分离的丘脑皮质中继神经元。在2 Hz刺激过程中，高压激活的LVA Ca2 +电流没有明显降低。 Ca2 +成像实验表明，细胞内Ca2 +水平的增加与HVA Ca2 +电流幅度的减少之间存在密切的相关性。对HVA Ca2 +电流的进一步检查显示了“ U形”灭活曲线和随时间变化的灭活过程，该过程可以通过两个指数函数来描述。 ``U形''显着降低，电流幅度显着增加，时间依赖性灭活显示以Ba2 +为电荷载体，激活cAMP / PKA途径以及应用磷酸酶抑制剂（子囊霉素）后呈指数下降，calyculin A）。蛋白质印迹分析和子囊霉素的作用表明钙调神经磷酸酶参与了失活过程。通过亚型特异性阻滞剂分离HVA Ca2 +电流成分显示，时间依赖性失活，失活曲线和电流幅度的变化主要由L型和N型Ca2 +电流引起。此外，Ca2 +依赖的失活在刺激方案中是有效的，模拟了补益动作电位的激发。这些数据表明通过磷酸化对L型和N型Ca2 +通道的调节，在上升的脑干系统活动期间共同导致细胞内Ca2 +内流增加，后者在清醒状态下发生。

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