Figure 5.

Effects of α7–nAChR crosslink on RRP capacity and kinetics. A, Sample traces (left) and summary charge-transfer graphs (right) of EPSCs induced by hypertonic sucrose (0.5 m) in control (Ctrl, black trace) and crosslinked α7–nAChR (α7X, red trace) conditions. Hypertonic sucrose was puffed using a multibarrel pipette (see Materials and Methods) onto the patched neuron for 4 s in the presence of 1 μm TTX and 50 μm gabazine. Charge transfer during the initial (Charge 0–2 s) and steady-state responses (Charge 2–4 s) were quantified to estimate the RRP size (n = 17 neurons, 4 culture sets for both conditions; mean ± SEM; Student's t test, *p < 0.05). B, Cumulative charge transfer as a function of time (left) and the corresponding kinetic analyses (right) of sucrose-induced EPSCs in control (Ctrl, black) and crosslinked (α7X, red) conditions. Dotted gray line shows the scaled control (Ctrl scaled) for comparison. The integrated charge transfer was fitted with a double-exponential function to determine kinetic parameters for the fast and slow components (τ_fast and τ_slow, respectively) and for their amplitudes (A_fast and A_slow). C, Representative EPSC traces (left) and summary graphs (right) showing absolute and normalized data for RRP recovery over three sucrose applications at 30 s interpuff intervals in control (black) and crosslinked (red) conditions. RRP recovery was calculated by dividing the second and third sucrose-induced charge transfer by the value of the first and then normalized to the first current amplitude (n = 19 neurons, 4 culture sets for both conditions; mean ± SEM; Student's t test, *p < 0.05).