Changes in intracellular Ca²⁺ concentration ([Ca²⁺]_i) produced by ryanodine receptor (RyR) agonist, caffeine (caf), and ionotropic agonists: N-methyl-d-aspartate (NMDA) receptor (NMDAR) agonist, NMDA and P2X7 receptor (P2X7R) agonist, 3′-O-(4-benzoyl)benzoyl adenosine 5′-triphosphate (BzATP) were measured in cultured mouse cortical astrocytes loaded with the fluorescent calcium indicator Fluo3-AM in a confocal laser scanning microscope. In mouse astrocytes cultured in standard medium (SM), treatment with caf increased [Ca²⁺]_i, with a peak response occurring about 10 min after stimulus application. Peak responses to NMDA or BzATP were observed about <1 min and 4.5 min post stimulus, respectively. Co-treatment with NMDA or BzATP did not alter the peak response to caf in astrocytes cultured in SM, the absence of the effects being most likely due to asynchrony between the response to caf, NMDA and BzATP. Incubation of astrocytes with neuron-condition medium (NCM) for 24 h totally abolished the caf-evoked [Ca²⁺]_i increase. In NCM-treated astrocytes, peak of [Ca²⁺]_i rise evoked by NMDA was delayed to about 3.5 min, and that induced by BzATP occurred about three minutes earlier than in SM. The results show that neurons secrete factors that negatively modulate RyR-mediated Ca²⁺-induced Ca²⁺ release (CICR) in astrocytes and alter the time course of Ca²⁺ responses to ionotropic stimuli.

细胞内Ca变化²⁺浓度（[钙²⁺ ]_我N-甲基：）由兰诺定受体（RyR的）激动剂，咖啡因（CAF），和离子型激动剂产生的d天冬氨酸（NMDA）受体（NMDAR）激动剂，NMDA和 P2X7 受体 (P2X7R) 激动剂、3'-O-(4-苯甲酰基)苯甲酰腺苷 5'-三磷酸 (BzATP) 在共聚焦激光扫描显微镜下在装有荧光钙指示剂 Fluo3-AM 的培养的小鼠皮层星形胶质细胞中进行测量。在标准培养基 (SM) 中培养的小鼠星形胶质细胞中，用 caf 处理增加了 [Ca ²⁺ ] _i，在刺激应用后约 10 分钟出现峰值响应。分别在刺激后约 <1 分钟和 4.5 分钟观察到对 NMDA 或 BzATP 的峰值反应。与 NMDA 或 BzATP 共同处理不会改变在 SM 中培养的星形胶质细胞中对 caf 的峰值反应，没有影响最有可能是由于对 caf、NMDA 和 BzATP 的反应之间的不同步。星形胶质细胞与神经元条件培养基 (NCM) 孵育 24 小时完全消除了咖啡馆诱发的 [Ca ²⁺ ] _i增加。在 NCM 处理的星形胶质细胞中，[Ca ²⁺ ] _{i 的}峰值NMDA 引起的上升延迟到约 3.5 分钟，而 BzATP 引起的上升比 SM 早约 3 分钟。结果表明，神经元分泌的因子对星形胶质细胞中RyR 介导的 Ca ²⁺诱导的 Ca ²⁺释放 (CICR)产生负调节，并改变 Ca ²⁺对离子性刺激的反应时间过程。