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[机电和反应扩散系统在神经元内信息处理中的作用:钙内流和细胞内钙对环磷酸腺苷活性的影响]

[The role of electro-mechanical and reaction-diffusion systems in the intra-neuron processing of information: effect of in-flow of calcium and intracellular calcium on cAMP activity].

作者信息

Liberman E A, Minina S V, Modebadze Z V, Mamikonova T A, Miakotina O L

出版信息

Biofizika. 1986 Jan-Feb;31(1):87-93.

PMID:2420372
Abstract

Influx of calcium ions cannot control a generatory potential induced by the intraneuronal system because calcium ions enter the cell during impulses. These impulses are the result of problem solving and must not influence directly the generatory potential. Therefore cAMP and not calcium controls the permeability of sodium and potassium channels from the inside of the neuron. However the calcium ions and membrane potential of mitochondria affect the impact of cAMP injections. An increase in the intracellular concentration of free Ca2+ induced by the injection of Ca-EGTA buffer with 5.10(-7) M free Ca2+, electric excitation, uncouplers of oxidative phosphorylation or arsenate leads to an increase of cAMP-dependent depolarization and the inward current. The injection of Ca-EGTA buffer with 10(-5) M free Ca2+ and drop in [Ca2+]in by EGTA as well as generation of impulses after cAMP injection decrease the cAMP effect. As rise in [Ca2+]in activates phosphodiesterase and uncouples oxidative phosphorylation, and vanadate in contrast to arsenate suppresses the cAMP effect, a hypothesis is advanced that activating effect of calcium on cAMP action is associated with neuron deenergization.

摘要

钙离子内流无法控制由神经元内系统诱导产生的动作电位,因为钙离子在冲动期间进入细胞。这些冲动是解决问题的结果,且绝不能直接影响动作电位。因此,是环磷酸腺苷(cAMP)而非钙离子从神经元内部控制钠通道和钾通道的通透性。然而,钙离子和线粒体膜电位会影响cAMP注射的效果。注射含5×10⁻⁷M游离钙离子的Ca-EGTA缓冲液、电刺激、氧化磷酸化解偶联剂或砷酸盐所诱导的细胞内游离Ca²⁺浓度增加,会导致cAMP依赖性去极化和内向电流增加。注射含10⁻⁵M游离钙离子的Ca-EGTA缓冲液以及EGTA使细胞内[Ca²⁺]降低,还有cAMP注射后产生的冲动,都会降低cAMP的作用效果。由于细胞内[Ca²⁺]升高会激活磷酸二酯酶并使氧化磷酸化解偶联,且钒酸盐与砷酸盐相反会抑制cAMP的作用效果,因此提出一个假设:钙离子对cAMP作用的激活效应与神经元能量耗尽有关。

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