Enhancement of neuronal calcium channel currents by the nootropic agent, nefiracetam (DM-9384), in NG108-15 cells
1994; Elsevier BV; Volume: 642; Issue: 1-2 Linguagem: Inglês
10.1016/0006-8993(94)90913-x
ISSN1872-6240
AutoresMitsunobu Yoshii, Shigeo Watabe,
Tópico(s)Ion channel regulation and function
ResumoEffects of nootropic agents on neuronal calcium channels were studied in NG108-15 cells using the whole-cell patch-clamp technique. Nefiracetam (DM-9384) at a concentration of 1 μM increased a long-lasting component of calcium channel currents two-fold without affecting a transient component. The dose-response relationship yielded a bell-shaped curve with a peak at 1 μM. Similar, but slightly less potent effects were observed by aniracetam. Dibutyryl cyclic AMP (1 mM) also enhanced the currents, which were not further increased by nefiracetam, or vice versa. The currents enhanced by nefiracetam were markedly reduced by nifedipine (10 μM), an ‘L-type’ calcium channel blocker. Cells treated with pertussis toxin (PTX; 500ng/ml, > 20h) to inactivate inhibitory G-proteins were apparently insensitive to nefiracetam. The results suggest that the nootropic agents may enhance the activity of neuronal L-type calcium channels under the regulation of inhibitory G-proteins and possibly, cyclic AMP-dependent processes.
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