Pii: S0306-4522(98)00475-8
نویسنده
چکیده
Whether exocytosis evoked by a given releasing stimulus from different neuronal families or by different stimuli from one neuronal population occurs through identical mechanisms is unknown. We studied the release of [3H]noradrenaline, [3H]acetylcholine and [3H]dopamine induced by different stimuli from superfused rat brain synaptosomes pretreated with tetanus toxin or botulinum toxin F, known to block exocytosis by cleaving VAMP/synaptobrevin. The external Ca21-dependent [3H]transmitter overflows evoked by KCl were similarly inhibited by tetanus toxin or botulinum toxin F; the toxins cleaved similar amounts of synaptosomal synaptobrevin, as determined by western blot analysis, suggesting prevalent involvement of synaptobrevin-II. GABA uptake-mediated release of the three [3H]transmitters was that differentially sensitive to the toxins: only the release of [3H]noradrenaline, which is dependent on external Ca21, but not of [3H]acetylcholine and [3H]dopamine was blocked. Neither toxin affected the [3H]transmitter overflows evoked by the Ca21 ionophore ionomycin. Cadmium blocked the K-evoked release of all [3H]transmitters and the GABA-evoked release of [3H]noradrenaline; the GABA-evoked releases of [3H]acetylcholine and [3H]dopamine and those elicited by ionomycin were insensitive to cadmium. The results suggest that tetanus toxin and botulinum toxin F selectively affect exocytosis linked to activation of voltage-sensitive Ca21 channels; the Ca21-dependent, exocytotic-like release induced by stimuli not leading to activation of voltage-sensitive Ca21 channels seems insensitive to these clostridial toxins. q 1999 IBRO. Published by Elsevier Science Ltd.
منابع مشابه
Pii: S0306-4522(98)00353-4
D. L U P I , * t H. M. COOPER,J; A. F R O E H L I C H , * L. S T A N D F O R D , § M. A. McCALL!§ and R. G. F O S T E R * ¶ *Department of Biology, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BB, U.K. tCentro Marino Internazionale (IMC), Torregrande-Oristano, Italy ~Cerveau et Vision, I.N.S.E.R.M. U-371, Avenue Doyen Lepine, 69500 Bron, France §Departm...
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