High water permeabilities permit rapid adjustments of glial volume upon changes in external and internal osmolarity, and pathologically altered intracellular chloride concentrations ([Cl^–]_int) and glial cell swelling are often assumed to represent early events in ischemia, infections, or traumatic brain injury. Experimental data for glial [Cl^–]_int are lacking for most brain regions, under normal as well as under pathological conditions. We measured [Cl^–]_int in hippocampal and neocortical astrocytes and in hippocampal radial glia-like (RGL) cells in acute murine brain slices using fluorescence lifetime imaging microscopy with the chloride-sensitive dye MQAE at room temperature. We observed substantial heterogeneity in baseline [Cl^–]_int, ranging from 14.0 ± 2.0 mM in neocortical astrocytes to 28.4 ± 3.0 mM in dentate gyrus astrocytes. Chloride accumulation by the Na⁺-K⁺-2Cl^– cotransporter (NKCC1) and chloride outward transport (efflux) through K⁺-Cl^– cotransporters (KCC1 and KCC3) or excitatory amino acid transporter (EAAT) anion channels control [Cl^–]_int to variable extent in distinct brain regions. In hippocampal astrocytes, blocking NKCC1 decreased [Cl^–]_int, whereas KCC or EAAT anion channel inhibition had little effect. In contrast, neocortical astrocytic or RGL [Cl^–]_int was very sensitive to block of chloride outward transport, but not to NKCC1 inhibition. Mathematical modeling demonstrated that higher numbers of NKCC1 and KCC transporters can account for lower [Cl^–]_int in neocortical than in hippocampal astrocytes. Energy depletion mimicking ischemia for up to 10 min did not result in pronounced changes in [Cl^–]_int in any of the tested glial cell types. However, [Cl^–]_int changes occurred under ischemic conditions after blocking selected anion transporters. We conclude that stimulated chloride accumulation and chloride efflux compensate for each other and prevent glial swelling under transient energy deprivation.

高透水性允许根据外部和内部渗透压的变化快速调整神经胶质体积，并且病理改变的细胞内氯化物浓度 ([Cl ^– ] _int ) 和神经胶质细胞肿胀通常被认为代表缺血、感染或创伤性脑损伤的早期事件. 在正常和病理条件下，大多数大脑区域缺乏神经胶质 [Cl ^– ] _{int 的}实验数据。我们测量了 [Cl ^– ] _int在室温下使用荧光寿命成像显微镜和氯化物敏感染料 MQAE 在海马和新皮质星形胶质细胞以及急性鼠脑切片中的海马径向胶质样 (RGL) 细胞中进行检测。我们观察到基线 [Cl ^– ] _{int 的}显着异质性，范围从新皮质星形胶质细胞的 14.0 ± 2.0 mM 到齿状回星形胶质细胞的 28.4 ± 3.0 mM。Na ⁺ -K ⁺ -2Cl ^–协同转运蛋白 (NKCC1) 的氯化物积累和通过 K ⁺ -Cl ^–协同转运蛋白 (KCC1 和 KCC3) 或兴奋性氨基酸转运蛋白 (EAAT) 阴离子通道控制 [Cl ^– ]_整数在不同的大脑区域不同程度。在海马星形胶质细胞中，阻断 NKCC1 会降低 [Cl ^– ] _int，而 KCC 或 EAAT 阴离子通道抑制作用很小。相比之下，新皮质星形胶质细胞或 RGL [Cl ^– ] _int对氯离子向外转运的阻断非常敏感，但对 NKCC1 抑制作用不敏感。数学模型表明，与海马星形胶质细胞相比，新皮质中较高数量的 NKCC1 和 KCC 转运蛋白可以解释较低的 [Cl ^– ] _int。在任何测试的神经胶质细胞类型中，模拟缺血长达 10 分钟的能量消耗不会导致 [Cl ^– ] _{int 的}显着变化。然而，[Cl^– ]在阻断选定的阴离子转运蛋白后，在缺血条件下发生_int变化。我们得出结论，受刺激的氯离子积累和氯离子外流相互补偿并防止短暂能量剥夺下的神经胶质肿胀。