Nitric oxide induces calcium-dependent [3H]dopamine release from striatal slices.
Hydroxylamine (0.01-30 mM), a nitric oxide (NO) generator, produced a concentration-dependent release of [3H]dopamine ([3H]DA) from rat striatal slices. Hemoglobin (10 microM), a NO scavenger, reduced basal [3H]DA release and blocked hydroxylamine (100 microM)-stimulated [3H]DA efflux. Tetrodotoxin (0.5 microM) had no significant effect. Sodium cyanide was used as a model compound to test the possibility that NO acted through blockade of mitochondrial electron transport. Calcium-free experimental buffer (1 mM EGTA) reduced basal release and the hydroxylamine response, while sodium cyanide-induced release did not change under these experimental conditions. Cadmium (200 microM), a non-selective inhibitor of voltage-dependent calcium channels, reduced the hydroxylamine response by 69%. Methylene blue (10 microM), an inhibitor of guanylate cyclase, produced a 3-fold increase in the basal release but had no significant effect on the hydroxylamine response. These data suggest that NO induces calcium-dependent [3H]DA release from the striatum via a mechanism which is independent of blockade of electron transport or activation of guanylate cyclase.
Lonart
G
G
Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston 77555-1031.
Cassels
K L
KL
Johnson
K M
KM
D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D004347:Drug Interactions; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000502:physiology; D006454:Hemoglobins / Q000494:pharmacology; D019811:Hydroxylamine; D006898:Hydroxylamines / Q000494:pharmacology; D008751:Methylene Blue / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012636:Secretory Rate / Q000187:drug effects; D012966:Sodium Cyanide / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D006454:Hemoglobins; D006898:Hydroxylamines; D002104:Cadmium; D019811:Hydroxylamine; D009569:Nitric Oxide; D013779:Tetrodotoxin; D006162:Guanylate Cyclase; D012966:Sodium Cyanide; D002118:Calcium; D008751:Methylene Blue; D004298:Dopamine