FIGURE 9:

Expression of Doc2β-C2A_clmB_clm enhanced the size of the RRP and did not affect SV replenishment in wt hippocampal neurons. (A) Representative EPSCs evoked by a train of 40 action potentials (20 Hz) recorded from wt neurons with and without overexpression of Doc2β-wt or Doc2β-C2A_clmB_clm. (B) The amplitude of each peak vs. time. (C) The data in B normalized to the amplitude of the first peak. (D) Cumulative phasic charge transfer plotted vs. time. Data points from 1.5 to 2.0 s were fitted with a linear function, revealing a steady-state of SV release (inset). (E) The RRP size was determined by extrapolating the linear fit through the y-intercept shown in D. The RRP size was increased by expression of Doc2β-C2A_clmB_clm but not Doc2β-wt. (F) The replenishment rate was measured by normalizing the slope of the linear fitting trace (as shown in D) to the RRP size obtained in E. The replenishment rate was unaffected by expression of Doc2β-wt or Doc2β- C2A_clmB_clm. (G) Representative hypertonic sucrose responses recorded from wt neurons and neurons expressing Doc2β-wt or Doc2β-C2A_clmB_clm. (H) The RRP size was measured by integrating the sucrose responses and was, again, increased by expression of Doc2β-C2A_clmB_clm but not Doc2β-wt. (I) SV release probability (P_vr) calculated by normalizing the total EPSC charge transfer to the RRP size measured using 20-Hz train stimulation from E. Data are represented as mean ± SEM. *p < 0.05, Student's t test. The number of cells, n, is indicated in the bar graphs; in all cases recordings were obtained using neurons from three or more independent litters of mice.