The effect of verapamil, a calcium-entrance blocker, on K+-evoked release of endogenous dopamine from tuberoinfundibular neurons incubated in vitro was studied. This compound, added to the incubation medium, at the dose of 10-6 M, significantly reinforced K+-induced dopamine release, whereas, at higher doses (10-5, 5 × 10-5 and 10-4 M), it completely prevented the stimulated dopamine release. The results obtained with the higher doses showed the calcium dependence of K+-evoked release of endogenous dopamine from central neurons. The opposite effect, seen with the lower dose of verapamil, could be due to different pharmacological properties of the drug.
- calcium entry blockers
- dopamine release
- tuberoinfundibular dopaminergic neurons
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