Characterization of voltage dependent calcium channels on the lateral olivocochlear efferent fibers of the guinea pig.
Using in vitro superfusion technique the release of [3H]-dopamine from the lateral olivocochlear efferent fibers of the cochlea was investigated. Our previous study gave the first neurochemical evidence for the transmitter role of dopamine and proved its neuronal origin. Using specific antagonists now we characterized the voltage-dependent calcium channels (VDCCs) involved in the release of dopamine evoked by electrical stimulation of the cochlear tissue. Verapamil or nifedipine, and Ni2+ failed to affect the release, indicating that neither L-, nor T-type VDCCs are essential for the release process. The fact that omega-conotoxin inhibited the release of dopamine from lateral olivocochlear efferent fibers suggests, that N-type VDCCs are required for the calcium influx during electrical stimulation. These VDCCs could be presynaptic targets of modulation of the dopamine release under pathological conditions or in therapy.
Gáborján
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Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest.
Vizi
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D000818:Animals; D015220:Calcium Channels / Q000378:metabolism* / Q000502:physiology*; D003051:Cochlea / Q000378:metabolism* / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism; D004558:Electric Stimulation; D006168:Guinea Pigs; D008297:Male; D009847:Olivary Nucleus / Q000378:metabolism* / Q000502:physiology*; D013997:Time Factors
D015220:Calcium Channels; D004298:Dopamine