Hof P R, Celio M R, Magistretti P J
Département de Pharmacologie, Centre Médical Universitaire, Geneva, Switzerland.
Brain Res Dev Brain Res. 1989 Mar 1;46(1):107-13. doi: 10.1016/0165-3806(89)90147-8.
K+, at concentrations reached in the extracellular space during neuronal activity (5-10 mM), promotes a time- and concentration-dependent hydrolysis of [3H]glycogen newly synthesized by mouse cerebral cortical slices. In the present study, the glycogenolytic action of K+ was examined in the neocortex of the quaking mouse, a spontaneously epileptic mutant characterized by deficient myelination of the CNS. The potency and efficacy of K+ in eliciting glycogen hydrolysis was greatly enhanced in cerebral cortical slices prepared from homozygous quaking mice (qk/qk) older than 7 weeks of age, indicating a supersensitive response to a metabolic action of the ion. A detailed ontogenic analysis showed an evolution of the supersensitive response to K+ which is reminiscent of the previously described increase in the number of alpha 2-adrenoreceptors in the brainstem of this mutant. In contrast to the altered response to K+, the glycogenolytic action of noradrenaline and vasoactive intestinal peptide reported earlier was equally expressed in qk/qk and in their unaffected littermates.
在神经元活动期间细胞外空间中达到的浓度（5 - 10 mM）下，钾离子（K⁺）会促进小鼠大脑皮层切片新合成的[³H]糖原发生时间和浓度依赖性水解。在本研究中，在颤抖小鼠的新皮层中检测了K⁺的糖原分解作用，颤抖小鼠是一种自发性癫痫突变体，其特征是中枢神经系统髓鞘形成缺陷。在7周龄以上的纯合颤抖小鼠（qk/qk）制备的大脑皮层切片中，K⁺引发糖原水解的效力和效能大大增强，表明对该离子的代谢作用有超敏反应。详细的个体发育分析显示对K⁺的超敏反应的演变，这让人想起先前描述的该突变体脑干中α₂ - 肾上腺素能受体数量的增加。与对K⁺的反应改变相反，先前报道的去甲肾上腺素和血管活性肠肽的糖原分解作用在qk/qk及其未受影响的同窝仔鼠中表达相同。
