Quantum Characteristics of Neurotransmitter Release in GABA-ergic Synapses of Cultured Neurons of the Rat Spinal Cord

摘要

Using the whole-cell patch-clamp technique and stimulation of a single presynaptic terminal, we studiedpeculiarities of GABA release in inhibitory synapses of cultured neurons of the rat spinal cord. Analyzing theamplitude distributions of evoked inhibitory postsynaptic currents, we estimated the main quantum parametersof transmitter release. It was demonstrated that the minimum transmitter release in GABA-ergic synapsesof spinal neurons cultured 9 to 11 days is multiquantum (packets containing at least 2 or 3 quanta). Thedistribution of the number of released quanta sufficiently agreed with that theoretically calculated accordingto the Poisson law. It is hypothesized that the minimum simultaneous two (three-)-quantum release of GABAin synapses of spinal neurons can be related to synchronous involvement of two closely adjacent excitedterminals, each of which possesses one active zone, or of one terminal with two active zones.