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Independent receptors for diadenosine pentaphosphate and ATP in rat midbrain single synaptic terminals
Author(s) -
DíazHernández M.,
Pintor J.,
Castro E.,
MirasPortugal M. T.
Publication year - 2001
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.0953-816x.2001.01703.x
Subject(s) - ionotropic effect , receptor , purinergic receptor , metabotropic receptor , extracellular , chemistry , p2y receptor , adenosine triphosphate , neurotransmission , biophysics , glutamate receptor , biochemistry , microbiology and biotechnology , biology
Diadenosine pentaphosphate (Ap 5 A) and adenosine 5′‐triphosphate (ATP) stimulate a intrasynaptosomal calcium concentration [Ca 2+ ] i increase via specific purinergic receptors in rat midbrain synaptosomes, although nothing is known about their distribution in presynaptic terminals. A microfluorimetric technique to measure [Ca 2+ ] i increase using the dye FURA‐2AM, has permitted study of the presence of dinucleotide and P2X receptors in independent isolated synaptic terminals. Our results demonstrate the existence of three populations of synaptosomes: one with dinucleotide receptors (12%), another with P2X receptors (20%) and a third with both (14%). It has been possible to demonstrate that the activation of these receptors occurs only in the presence of extracellular Ca 2+ and that it is also coupled with voltage‐dependent Ca 2+ channels. Finally 54% of the synaptosomes that responded to K + did not present any calcium increase mediated by the nucleotides used. In summary, ATP and dinucleotides exhibit specific ionotropic receptors that can coexist or not on the same synaptic terminal.