Hosoi Rie, Matsuyama Yasuyo, Hirose Shin-ichiro, Koyama Yutaka, Matsuda Toshio, Gee Antony, Inoue Osamu
Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Brain Res. 2009 Feb 9;1253:69-73. doi: 10.1016/j.brainres.2008.11.068. Epub 2008 Dec 6.
To investigate the regulation mechanism of (14)C-acetate uptake in astrocytes, uptake experiments with cultured rat astrocytes were performed. In this study, we used a relatively low concentration (0.0185 mM) of (14)C-acetate. The uptake was dependent on pH and acetate concentration, and saturated by 10 mM acetate. Furthermore, the selective inhibition by p-(chloromercuri) benzenesulfonic acid (pCMBS) but not by alpha-cyano-3-hydroxycinnamate (CHC) showed that the monocarboxylate transporter-1 (MCT-1)-mediated transport system is essentially important in cultured rat astrocytes. A significant reduction (more than 30%) in (14)C-acetate uptake was observed with 0.5 mM fluorocitrate treatment, which indicated (14)C-acetate uptake in this study might reflect not only the transport process, but also the metabolic process. Glutamate significantly increased (14)C-acetate uptake. An increase in extracellular potassium concentration had no effect on (14)C-acetate uptake. The Ca(2+) ionophore A23187 caused a 40% reduction, and ouabain (inhibitor of Na(+)-K(+)-ATPase) and monensin (Na(+) ionophore) significantly decreased (14)C-acetate uptake by astrocytes. The combined use of ouabain and monensin caused significantly greater decreases than the addition of either chemical alone. These results suggest that glutamate stimulation and changes in Ca(2+) and Na(+) concentrations might have important roles in regulation of (14)C-acetate uptake in cultured rat astrocytes.
为了研究星形胶质细胞中¹⁴C - 醋酸盐摄取的调节机制，我们对培养的大鼠星形胶质细胞进行了摄取实验。在本研究中，我们使用了相对较低浓度（0.0185 mM）的¹⁴C - 醋酸盐。摄取依赖于pH值和醋酸盐浓度，在10 mM醋酸盐时达到饱和。此外，对氯汞苯磺酸盐（pCMBS）而非α - 氰基 - 3 - 羟基肉桂酸盐（CHC）的选择性抑制表明，单羧酸转运体 - 1（MCT - 1）介导的转运系统在培养的大鼠星形胶质细胞中至关重要。用0.5 mM氟柠檬酸处理后，观察到¹⁴C - 醋酸盐摄取显著降低（超过30%），这表明本研究中的¹⁴C - 醋酸盐摄取可能不仅反映转运过程，还反映代谢过程。谷氨酸显著增加¹⁴C - 醋酸盐摄取。细胞外钾离子浓度的增加对¹⁴C - 醋酸盐摄取没有影响。钙离子载体A23187导致摄取降低40%，哇巴因（钠钾ATP酶抑制剂）和莫能菌素（钠离子载体）显著降低星形胶质细胞的¹⁴C - 醋酸盐摄取。哇巴因和莫能菌素联合使用导致下降幅度明显大于单独添加任何一种化学物质。这些结果表明，谷氨酸刺激以及钙离子和钠离子浓度的变化可能在培养的大鼠星形胶质细胞中¹⁴C - 醋酸盐摄取的调节中起重要作用。
