Effects of voltage-sensitive calcium channel blockers on extracellular dopamine levels in rat striatum.

摘要: Various subtypes of voltage-sensitive calcium channels (VSCCs) support the release dopamine (DA) in central nervous system. Using vivo microdialysis, we investigate influence these on dopaminergic terminals rat striatum. L-type (nifedipine-sensitive), N-type (omega-conotoxin GVIA-sensitive), or N- and P/Q-type MVIIC-sensitive) Ca2+ were blocked using selective antagonists injected locally, K+-evoked DA was measured freely moving animals. K+ (100 mM) induced a massive increase basal extracellular levels (930%) without significant effect metabolites DOPAC HVA, serotonin metabolite 5HIAA. Omega-conotoxin GVIA (1 microM) omega-conotoxin MVIIC significantly reduced by 55 62%, respectively. The simultaneous application two conotoxins at same concentration 66%. Nifedipine (10 had no K-evoked release, while neomycin, nonspecific VSCC blocker, produced highly decrease when applied 250 500 microM (56 75%, respectively). compounds. however, DOPAC, These results suggest that under high persistent conditions membrane depolarization (15 min, 10 mM K+), striatal is mainly mediated VSCCs.