title: The effects of a photosensitive nitric oxide donor on basal and electrically-stimulated dopamine efflux from the rat striatum in vitro.
abstract: The reported effects of nitric oxide (NO) on dopamine release from the striatum are variable and its precise effect on striatal nerve terminals is unclear. In the present study a novel method of applying NO to brain tissue in situ was employed. Photo-activation of Roussin's Black Salt (RBS), retained in isolated perfused brain tissue, was used to release NO at will upon illumination. Basal and electrically-stimulated dopamine efflux from the rat striatum in vitro was measured in real time using fast cyclic voltammetry. Illumination of an RBS pre-treated brain slice elicited a light intensity-related increase in basal dopamine efflux. Concomitantly there was a decrease in the level of electrically-stimulated dopamine efflux. Illumination in the absence of RBS pre-treatment had no effect on basal or stimulated dopamine efflux. The increase in basal dopamine efflux upon photo-activation of RBS was reduced by the presence of 10 microM oxyhaemoglobin, but was insensitive to the removal of extracellular calcium or the addition of 1 microM sulpiride. The decrease in electrically-stimulated dopamine efflux following illumination was not affected by the presence of either oxyhaemoglobin or sulpiride. It is concluded that NO, produced by photo-activation of RBS, releases dopamine from the rat striatum in vitro by a mechanism independent of extracellular calcium entry.
authors.affiliation: Glaxo Institute of Applied Pharmacology, Department of Pharmacology, University of Cambridge, U.K.
authors.forename: M D
authors.initials: MD
authors.lastname: Black
authors.forename: E K
authors.initials: EK
authors.lastname: Matthews
authors.forename: P P
authors.initials: PP
authors.lastname: Humphrey
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007502:Iron Chelating Agents / Q000494:pharmacology* / Q000528:radiation effects; D058085:Iron Compounds; D008027:Light; D008297:Male; D017072:Neostriatum / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D009603:Nitroso Compounds; D010108:Oxyhemoglobins / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013469:Sulpiride / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology* / Q000528:radiation effects
chemical_list: D007502:Iron Chelating Agents; D058085:Iron Compounds; D009573:Nitrites; D009603:Nitroso Compounds; D010108:Oxyhemoglobins; D014665:Vasodilator Agents; D009569:Nitric Oxide; C078952:Roussin's Black Salt; D013469:Sulpiride; D002118:Calcium; D004298:Dopamine