caa a22 4500 469078642 CHVBK 20180323132942.0 cr unu---uuuuu 170328e19921101xx s 000 0 eng 10.1007/BF00169016 doi (NATIONALLICENCE)springer-10.1007/BF00169016 Effects of the triazole derivative loreclezole (R72063) on stimulus induced ionic and field potential responses and on different patterns of epileptiform activity induced by low magnesium in rat entorhinal cortex-hippocampal slices [Elektronische Daten] [Chuan Zhang, Uwe Heinemann] Summary: Effects of loreclezole (R72063), a triazole derivative with anticonvulsant properties, were studied on field potentials in rat hippocampal slices and on different patterns of low Mg2+-induced epileptiform activity in combined entorhinal cortex-hippocampal slices. Lowering extracellular Mg2+ induced recurrent (10-60/min), short (40 - 80 ms) discharges in hippocampal areas CA1 and CA3. In the entorhinal cortex (EC) up to 90 s long ictaform events associated with large negative field potential and changes in the neuronal microenvironment were generated. These seizure like events changed their characteristics after one to two hours to recurrent discharges of 0.8 to 10 s. 20 μM loreclezole blocked the seizure like events in the entorhinal cortex completely 30-80 min after onset of application. The recurrent short discharges in the hippocampus were reliably blocked by 40 μM loreclezole 60 - 90 min after bath application with incomplete recovery after washout of several hours. The recurrent discharges in the entorhinal cortex were reliably blocked by 80 μM loreclezole applied for 80-100 min. Decreases in [Ca2+]0 and associated slow field potentials evoked by repetitive stimulation of the stratum radiatum were depressed in a dose dependent manner, while similar changes induced by alvear stimulation remained almost unaffected. A paired pulse stimulus paradigm used to test for effect of loreclezole on synaptically evoked transient field potentials in normal medium revealed interference with mechanisms involved in frequency potentiation. While responses to alvear stimulation were largely unaffected, the response to a paired pulse stimulus to stratum radiatum was depressed over the whole range of tested stimulus intervals (15 to 150 ms). The findings suggest that loreclezole has effects on different patterns of epileptiform activity induced by extracellular low Mg2+ possibly by interfering with processes leading to frequency potentiation. Springer-Verlag, 1992 Calcium nationallicence Epileptiform activity nationallicence Loreclezole nationallicence Low magnesium nationallicence Rat nationallicence Entorhinal cortex-hippocampus slices nationallicence Zhang Chuan Institut für Neurophysiologie, Zentrum für Physiologie und Pathophysiologie, Universität zu Köln, Robert-Koch-Strasse 39, W-5000, Köln 41, Federal Republic of Germany aut Heinemann Uwe Institut für Neurophysiologie, Zentrum für Physiologie und Pathophysiologie, Universität zu Köln, Robert-Koch-Strasse 39, W-5000, Köln 41, Federal Republic of Germany aut Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 346/5(1992-11-01), 581-587 0028-1298 346:5<581 1992 346 210 https://doi.org/10.1007/BF00169016 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00169016 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zhang Chuan Institut für Neurophysiologie, Zentrum für Physiologie und Pathophysiologie, Universität zu Köln, Robert-Koch-Strasse 39, W-5000, Köln 41, Federal Republic of Germany aut NATIONALLICENCE 700 1- Heinemann Uwe Institut für Neurophysiologie, Zentrum für Physiologie und Pathophysiologie, Universität zu Köln, Robert-Koch-Strasse 39, W-5000, Köln 41, Federal Republic of Germany aut NATIONALLICENCE 773 0- Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 346/5(1992-11-01), 581-587 0028-1298 346:5<581 1992 346 210 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer