Physiological separation of vesicle pools in low- and high-output nerve terminals

► The pools of synaptic vesicles are physiological differentiated in low- and high-output terminals. ► The antibiotic bafilomycin A1 blocks re-packaging of transmitter for fast recycling vesicles. ► Electrical activity and/or modulation by 5-HT can recruit vesicles from a reserve pool. ► Phasic type NMJs depress faster than tonic nerve terminals due to a high percent use of synaptic vesicles. ► Tonic terminals have a large reserve pool to recruit from with modulation by 5-HT.