Abstract
Involvement of P2X and P2Y receptors in various brain functions is now established. Yet unclear is the molecular mechanism of ATP release, especially in native tissues. To address this issue, we visualized changes in [ATP]o in acute brain slices. The slices of the hippocampus (CA1 and CA3), cortex and the nucleus of the solitary tract (NTS) were submerged in artificial cerebrospinal fluid containing luciferin and luciferase. The bioluminescence in a 320 μm X 240 μm field was detected with an image intensifier-coupled VIM camera with a 2.5- to 30-s exposure time. Continuous electrical stimulation delivered with a co-centric bipolar electrode (0.5 mA, 10 Hz) for 10-30 s markedly increased the light intensity (LI) around the electrode (in a radius of ~150 μm), which lasted during the stimuli and faded within 15-30 s in all three structures. This LI increase was not reproduced when the same locus was stimulated but observed similarly in the same slice when a distinct region was stimulated. Stimulation of the afferent fibers increased LI at the site of stimulation but not at the postsynaptic regions. The LI increase persisted in the presence of tetrodotoxin. Application of high [K+]o solution did not increase LI. It is concluded that electrical stimulation evokes ATP release at the site of stimulation, which was independent of action potential generation. Supported by Grants-in-Aid from the MECSST, Japan (No. 15650071). [Jpn J Physiol 54 Suppl:S150 (2004)]
