Failure of exogenous serotonin to inhibit the release of 3H-serotonin induced by electrical field stimulation in superfused goldfish brain slices.
1. Goldfish brain slices preloaded with 3H-serotonin were superfused with a solution of Krebs-Ringer phosphate at 30 degrees C in the presence of 1 microM fluoxetine, a serotonin uptake blocker. 2. The effects of exogenous serotonin, Ca2+ absence and Ca2+ chelation on basal and electrically-evoked tritium overflow were investigated. 3. Exogenous 1 or 10 microM serotonin did not alter the stimulated tritium overflow, but this was reduced to 44% and to 31% of the control value when the superfusion was performed in Ca2+-free and in Ca2+-free-EGTA conditions. 4. Neither Ca2+ absence,  Ca2+ chelation or 1 microM exogenous serotonin altered basal tritium efflux; however, the latter was significantly increased when the superfusion was performed in the presence of 10 microM serotonin.
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000502:physiology; D004558:Electric Stimulation; D005246:Feedback; D006054:Goldfish; D066298:In Vitro Techniques; D011985:Receptors, Serotonin / Q000502:physiology; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D013569:Synapses
D011985:Receptors, Serotonin; D012701:Serotonin; D002118:Calcium