• P W L Tas, C Eisemann, and N Roewer.
• Klinik für Anaesthesiologie, der Universität Würzburg, Josef-Schneider Strasse 2, 97080 Würzburg, Germany. ptas@anaesthesie.uni-wuerzburg.de
• Neurosci. Lett. 2003 Mar 6;338(3):229-32.

AbstractPrimary cultures of rat hippocampal neurons were loaded with the Ca(2+)-indicator fluo-3 and studied with a confocal laser microscope. In Mg(2+)-free medium the cultures showed spontaneous synchronized calcium oscillations. These oscillations derived from excitatory signal transmission by N-methyl-D-aspartate and (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid/kainate receptors and were modulated by gamma-aminobutyric acid(A) receptors. The oscillations were dose-dependently depressed by adenosine (IC50=2 microM) or by 2-chloro-N6-cyclopentyladenosine a specific adenosine A1 receptor agonist (IC50=40 nM). These effects were reverted by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a specific adenosine A1 receptor antagonist. The volatile anesthetic isoflurane also depressed these spontaneous calcium oscillations in a dose dependent manner (IC50=0.25 MAC, Minimum Alveolar Concentration). The isoflurane-induced inhibition was partly reversed in 29-38% of the neurons by DPCPX, indicating that the anesthetic activates this receptor possibly by increasing the extracellular concentration of adenosine.

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