FIGURE 2.

Diminishing Ca²⁺ influx by reducing extracellular [Ca²⁺] neither changed the size of EPSC nor the proportion of compact EPSCs. (A) Example traces of recordings before, during and after the perfusion of 0 mM Ca²⁺ + 2 mM EGTA. The frequency suddenly dropped to zero when the [Ca²⁺]_e was completely removed. The insets show an example of a real event and of noise: a real sEPSC has slower time constant while a noise has rather fast time constant and an up-and-down signal. (B1,C1) Cumulative probability function of the compact EPSC amplitude (left) and charge (right) before (B1) and during perfusion of 0 mM [Ca²⁺]_e + 2 mM EGTA (C1). The bold solid line is the mean of all recordings in each experiment group. For comparison with the 0 mM Ca²⁺ condition, the mean of the control condition is shown on panel (C1) as bold dashed line. (B2,C2) Histogram of compact EPSC amplitude (left) and charge (right) from a representative bouton before (B2) and in the transition time while perfusing 0 mM [Ca²⁺]_e + 2 mM EGTA (C2). The dashed line is a Gaussian function fitted to the data. (D) Box-Whisker plot of EPSC frequency in different experimental conditions (n = 7 in control condition; n = 6 in 0 mM Ca²⁺+ 2 mM EGTA). There was no statistically significant difference between the two groups (Wilcoxon Rank test, p = 0.16). (E) Box-Whisker plot of compact EPSC percentage in different experimental conditions. There is no significant difference between the control condition and the reduced Ca²⁺ influx condition (p = 0.67). Box plots show 10, 25, 50, 75, and 90th percentiles with the individual data points overlaid.