Short communication Tetanus-induced asynchronous GABA release in cultured hippocampal

Asynchronous GABA release was studied in cultured hippocampal neurons using paired whole-cell recordings. Tetanization of the presynaptic GABAergic neuron was accompanied by a train of IPSCs which showed tetanic depression. Asynchronous IPSCs (asIPSCs) also developed during the train and continued for 1.8560.3 s after the stimulation. The threshold frequency for evoking asIPSCs was 10 21 Hz, while maximal asynchronous activity was achieved at 40 Hz. Perfusion with EGTA-AM blocked asIPSCs. The elevation of (Ca )i that accompanies presynaptic action potential firing triggers asynchronous release of GABA vesicles, thereby counteracting tetanic depression of synchronous IPSCs. © 2000 Elsevier Science B.V. All rights reserved. Theme: Excitable membranes and synaptic transmission Topic: Mechanisms of neurotransmitter release