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Figure 2 | Molecular Brain

Figure 2

From: Action potential evoked transmitter release in central synapses: insights from the developing calyx of Held

Figure 2

Summary of developmental changes in the temporal profiles of the local [Ca2+] i transient seen by the Ca2+ sensor and glutamate release during an AP. A, Schematic diagram illustrating developmental tightening in the coupling between synaptic vesicles and VGCCs. Immature calyces (A1) have fewer docked vesicles that are loosely coupled to VGCCs, whereas mature calyces (A2) possess approximately a twofold larger number of release-competent vesicles that more closely colocalize with Ca2+ channels. B, Timing (right) of the local [Ca2+]i (red) and release (blue) transients relative to the presynaptic APs (black) for P9--P11 (B1) and P16--P19 (B2) calyces. Traces in B1 and B2 were aligned relative to the onset of the presynaptic APs (dotted line). The average time course of the AP-evoked local [Ca2+]i transients was obtained from 16 of P9--P11 and 18 of P16--P19 synapses. The peak of the local [Ca2+]i transient occurred ~410 μs earlier in mature synapses, because of their faster and briefer presynaptic APs (Image © Wang et al., 2008).

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