A readily releasable pool of single inhibitory boutons in culture.
The number of presynaptic vesicles that are immediately available for release, the readily releasable pool (RRP), is a strong determinant of synaptic strength and plasticity. The properties of the RRP in individual GABAergic synapses were examined in superior colliculus cultures. The RRP was depleted by high frequency trains and cumulative evoked IPSC amplitudes (CA) were calculated. The amplitude of monoquantal responses (q) was determined on the basis of mIPSC histograms. On average, the RRP, defined as CA/q, comprised about 10 vesicles. About 60% of the RRP could be released by a single stimulus. After depletion, the RRP was replenished with a time constant of about 14 s. These data provide information for further studies on the capacity of individual inhibitory synapses to modulate sensory information transfer.
Kirischuk
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S
Developmental Physiology, Johannes Muller Institute of Physiology, Humboldt University Medical School (Charite), Berlin, Germany.
Grantyn
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R
D000818:Animals; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005260:Female; D005456:Fluorescent Dyes; D007091:Image Processing, Computer-Assisted; D018377:Neurotransmitter Agents / Q000378:metabolism / Q000502:physiology*; D009924:Organ Culture Techniques; D011247:Pregnancy; D017729:Presynaptic Terminals / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013477:Superior Colliculi / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D005456:Fluorescent Dyes; D018377:Neurotransmitter Agents; D005680:gamma-Aminobutyric Acid