Characterization of DIDS-sensitive ATP accumulation in brain synaptic vesicles

ATP is an excitatory neurotransmitter in the central and peripheral nervous system. We investigated ATP accumulation in highly purified brain synaptic vesicles (SVs). Based on the amount of ATP accumulated in SVs under the conditions used, ATP is not transported against a concentration gradient but rather appears to have a ΔμH+-independent mechanism. ATP transport was inhibited by DIDS and NEM, but was not affected by Mg2+ or by pre-incubation with nucleotides. These results suggest a unique transport mechanism that does not involve exchange with other nucleotides or protons, unlike other known neurotransmitter transport systems.