BA2+ DOES NOT SUPPORT SYNAPTIC VESICLE RETRIEVAL IN RAT CEREBROCORTICAL SYNAPTOSOMES

To investigate whether any specific requirement for extracellular Ca2 exists in the control synaptic vesicle retrieval, we examined the abi lity of the divalent cation Ba2+ to substitute for Ca2+ in both vesicl e exocytosis and endocytosis. Ba2+ stimulated glutamate release from r at cerebrocortical synaptosomes. Ba2+-evoked release was inhibited by bafilomycin A1, indicating release was via exocytosis of synaptic vesi cles. However, Ba2+ did not stimulate vesicle retrieval, monitored by a FM2-10-based retrieval assay. Therefore synaptic Vesicle retrieval i n central nerve terminals has a specific requirement for extracellular Ca2+ and the Ca2+ receptor for retrieval has a different cation speci ficity to the Ca2+ receptor for exocytosis. (C) 1998 Elsevier Science Ireland Ltd. Ail rights reserved.