title: Depolarization-induced decreases in fluroescence intensity of gastro-intestinal quinacrine-binding nerves.
abstract: Quinacrine, a fluorescent antimalarial acridine derivative, selectively binds to a population of nerve cell bodies and nerve fibers in Auerbach's plexus and elsewhere in the gut. This quinacrine-binding, as measured by fluorescence intensity, is reduced if the nervous elements are depolarized by high K+ (80--150 MM) or veratridine (5 x 10(-5) M) during quinacrine incubation. A reduction of quinacrine-content in nerve terminals is also seen when depolarization (veratridine) takes place for 2 min after quinacrine-incubation, indicating a release of already bound quinacrine. If terminals are depolarized (high K+ or veratridine) before quinacrine incubation, a reduction of quinacrine content is also seen. The depolarization-induced reduction of quinacrine-binding is blocked by Ca2+-removal and, in the case of veratridine by tetrodotoxin. Our findings suggest that quinacrine binds to a compound that is released by nervous activity. Binding mechanism remains to be elucidated. The possibility that quinacrine visualized purine-rich structures is discussed.
mesh_terms: D000320:Adrenergic Fibers / Q000378:metabolism; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D007082:Ileum / Q000294:innervation*; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence; D009130:Muscle, Smooth / Q000294:innervation; D009197:Myenteric Plexus / Q000378:metabolism; D009412:Nerve Fibers / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D011796:Quinacrine / Q000378:metabolism*; D011955:Receptors, Drug / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects; D014701:Veratridine / Q000494:pharmacology
chemical_list: D011955:Receptors, Drug; D014701:Veratridine; D011796:Quinacrine; D011188:Potassium; D009638:Norepinephrine