Ca2+-dependent and -independent mechanisms of ischaemia-evoked release of [3H]-dopamine from rat striatal slices.
1. Ischaemia was induced by 5 min of deprivation of glucose and an additional 5 min of deprivation of glucose and oxygen from Mg(2+)-free artificial cerebrospinal fluid in vitro. 2. During the ischaemic period, 11 +/- 1.5% of the total [3H]-dopamine ([3H]-DA) was released into the incubation medium. 3. Ischaemia-evoked release of [3H]-DA from striatal slices was attenuated by tetrodotoxin (TTX), MgSO4, dizocilpine, ketamine, 6,7-dinitroquinoxaline-2,3-dione (DNQX) or carbetapentane. 4. Release of [3H]-DA was attenuated by verapamil, omega-conotoxin GVIA and dantrolene. 5. Nomifensin inhibited the ischaemia-induced release of [3H]-DA. 6. Omission of Ca(2+) from incubation media potentiated ischaemia-evoked [3H]-DA release. The inhibitory effect of nomifensin was potentiated in Ca(2+)-free incubation media. 7. These results suggest that ischaemia induces release of [3H]-DA by dual mechanisms; one is Ca(2+)-dependent exocytosis and the other is reversal of transporter.
Kim
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KW
Department of Pharmacology, Chonbuk National University Medical School, Republic of Korea.
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Eun
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D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D046508:Culture Techniques; D003517:Cyclopentanes / Q000494:pharmacology; D003620:Dantrolene / Q000494:pharmacology; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D007649:Ketamine / Q000494:pharmacology; D008278:Magnesium Sulfate / Q000494:pharmacology; D009627:Nomifensine / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D013779:Tetrodotoxin / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D003517:Cyclopentanes; D010455:Peptides; D011810:Quinoxalines; D009627:Nomifensine; C018861:carbetapentane; D013779:Tetrodotoxin; C056723:FG 9041; D007649:Ketamine; D016291:Dizocilpine Maleate; D008278:Magnesium Sulfate; D020866:omega-Conotoxin GVIA; D014700:Verapamil; D003620:Dantrolene; D002118:Calcium; D004298:Dopamine