Table 1.
Functional parameters of synaptic transmission in P16–21 Cplx1−/− and Cplx1+/+ mouse calyx of Held synapses
| Parameter | Cplx1+/+ | Cplx1−/− | Statistical significance of differences in mean |
|---|---|---|---|
| eEPSC peak amplitude | −11.88 ± 0.06 nA (n = 86) | −4.37 ± 0.04 nA (n = 83) | p < 0.001 |
| eEPSC rise time (20–80%) | 148 ± 2 μs (n = 86) | 154 ± 3 μs (n = 83) | n.s. |
| eEPSC weighted τdecay | 419 ± 11 μs (n = 85) | 440 ± 14 μs (n = 83) | n.s. |
| eEPSC half-width | 517 ± 8 μs (n = 86) | 552 ± 12 μs (n = 83) | p = 0.015 |
| mEPSC peak amplitude | −62.1 ± 2.9 pA (n = 39) | −63.6 ± 2.4 pA (n = 55) | n.s. |
| mEPSC weighted τdecay | 240 ± 8 μs (n = 39) | 238 ± 6 μs (n = 55) | n.s. |
| mEPSC frequency | 4.79 ± 0.43 s−1 (n = 39) | 2.14 ± 0.19 s−1 (n = 55) | p < 0.001 |
| Peak release ratea | 823 ± 62 SV/ms (n = 24) | 309 ± 36 SV/ms (n = 36) | p < 0.001 |
| Quantal content mb | 287 ± 21 SV (n = 38) | 113 ± 13 (n = 55) | p < 0.001 |
| Presynaptic ICa(V)c | −1.49 ± 0.08 nA (n = 20) | −1.44 ± 0.09 nA (n = 28) | n.s. |
| RRP sized | 351 ± 51 fF = 4388 ± 638 SV (n = 13) | 368 ± 39 fF = 4600 ± 488 SV (n = 18) | n.s. |
| Release probability pre | 13.1 ± 1.0% (n = 38) | 4.9 ± 0.6% (n = 55) | p < 0.001 |
| Asynchronous release ratef after high-frequency trains of: 100 Hz | 93 ± 17 SV/s (n = 28) | 1188 ± 92 SV/s (n = 44) | p < 0.001 |
| 200 Hz | 147 ± 26 SV/s (n = 32) | 1832 ± 143 SV/s (n = 47) | p < 0.001 |
| 300 Hz | 125 ± 37 SV/s (n = 15) | 2132 ± 172 SV/s (n = 43) | p < 0.001 |
n.s., Not significant.
aPeak release rates were obtained by deconvolving eEPSCs with the respective mEPSC waveforms (see Materials and Methods).
bm was calculated as the peak amplitude ratio eEPSCs/mEPSC and corrected with a factor of 1.4 to account for dispersion of release (Taschenberger et al., 2005).
cPeak ICa(V) values were obtained from currents evoked by step depolarizations of ≥10 ms.
dRRP size represents the sum of fast and slowly releasing vesicles as described by Sakaba and Neher (2001a) and was estimated from ΔCm measured in response to 50 ms step depolarizations.
epr was calculated as the ratio of m/(0.5 × RRP), assuming that those vesicles that contribute to synchronous AP-evoked release account for ∼50% of the total RRP (“fast releasing vesicles”; Sakaba and Neher, 2001a).
fAsynchronous release rates were obtained from line fits to the cumulative release measured after high-frequency trains (Fig. 7B) during a 100 ms interval starting 25 ms after the end of stimulation.