Research Report Characterization of 14 C-acetate uptake in cultured rat astrocytes Rie Hosoi a, ⁎ , Yasuyo Matsuyama a , Shin-ichiro Hirose a , Yutaka Koyama b,c , Toshio Matsuda c , Antony Gee d,e , Osamu Inoue a a Division of Health Sciences, Osaka University Graduate School of Medicine, 1-7 Yamadaoka, Suita, Osaka 565-0871, Japan b Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Nishikiori-Kita 3-11-1, Tonda-bayashi, Osaka, 584-8540, Japan c Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan d GlaxoSmithkline, Clinical Research Unit, ACCI, Addenbrookes Hospital Hills Road, Cambridge, CB2 2GG, UK e Department of Chemistry, Imperial College of London, South Kensington, London, SW7 2AZ, UK ARTICLE INFO ABSTRACT Article history: Accepted 19 November 2008 Available online 6 December 2008 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 α-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. © 2008 Elsevier B.V. All rights reserved. Keywords: 14 C-acetate uptake Astrocyte Glutamate Calcium Sodium 1. Introduction Acetate has been used as a probe to investigate brain metabolism, especially for examining astrocytic energy meta- bolism both in vitro and in vivo (Cerdan et al., 1990; Hassel et al., 1995). The preferential uptake of labeled acetate into astrocytes has been reported to be mainly attributable to the transport process of acetate (Waniewski and Martin, 1998) me- diated through the monocarboxylate transporter-1 (MCT-1), which is selectively present in astrocytes. Magnetic resonance spectroscopy (MRS) with 13 C-labeled acetate has been com- monly used to study the metabolic trafficking between astrocytes and neurons in intact brain (Cerdan et al., 1990). However, 13 C-acetate technique using MRS requires a con- BRAIN RESEARCH 1253 (2009) 69 – 73 ⁎ Corresponding author. Fax: +81 6 6879 2568. E-mail address: hosoi@sahs.med.osaka-u.ac.jp (R. Hosoi). 0006-8993/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.brainres.2008.11.068 available at www.sciencedirect.com www.elsevier.com/locate/brainres