Effect of changes in action potential shape on calcium currents and transmitter release in a calyx-type synapse of the rat auditory brainstem.
We studied the relation between the size of presynaptic calcium influx and transmitter release by making simultaneous voltage clamp recordings from presynaptic terminals, the calyces of Held and postsynaptic cells, the principal cells of the medical nucleus of the trapezoid body, in slices of the rat brainstem. Calyces were voltage clamped with different action potential waveforms. The amplitude of the excitatory postsynaptic currents depended supralinearly on the size of the calcium influx, in the absence of changes in the time-course of the calcium influx. This result is in agreement with the view that at this synapse most vesicles are released by the combined action of multiple calcium channels.
Borst
J G
JG
Max-Planck-Institut für Medizinische Forschung, Abt. Zellphysiologie, Heidelberg, Germany. borst@sunny.mpimf-heidelberg.mpg.de
Sakmann
B
B
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001933:Brain Stem / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology; D020013:Calcium Signaling / Q000502:physiology*; D066298:In Vitro Techniques; D018377:Neurotransmitter Agents / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000502:physiology*
D015220:Calcium Channels; D018377:Neurotransmitter Agents