| Abstract: | The calcium-channel ligand, nimodipine (Bay e 9736), in submicromolar concentrations (10(-7) to 10(-5) M), enhanced the potassium (25 mM) or electrical stimulation (1 Hz, 1 ms, 180 pulses) evoked release or 3H]dopamine from rat striatal slices, while it inhibited the release of 3H]acetylcholine. Nimodipine had similar effects on slices from the cerebral cortex loaded with 3H]dopamine or 3H]acetylcholine, the electrical stimulation evoked release of the catecholamine was enhanced, while release of 3H]acetylcholine was suppressed. The data indicate that nimodipine may distinguish between Ca2+ channels in dopaminergic and cholinergic nerve-terminals. The simultaneous elevation of dopamine release and suppression of acetylcholine release may prove useful in the treatment of Parkinson's disease. |
