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. 2017 Sep 5;114(38):E8081–E8090. doi: 10.1073/pnas.1702991114

Fig. 3.

Fig. 3.

Deletion of RBPs impairs the speed of both RRP emptying and RRP replenishment. (A, Left) Schematic of recording configuration. (Right) Representative postsynaptic recordings in an RBP WT (black) and an RBP DKO (blue) synapse. Transmitter release was triggered by presynaptic rod bipolar cell depolarization from −70 to −10 mV for 50 ms. All these experiments were performed in the presence of 1 mM BAPTA in the presynaptic pipette. (B) Summary graphs of RRP properties. RRP size and properties were estimated by recording EPSCs in AII cells after maximal activation of presynaptic bipolar cells, as indicated in A. From Left to Right, the following parameters are displayed: EPSC amplitude, EPSC charge transfer, EPSC 20 to 80% rise time, and EPSC decay time constant. Number of experiments: RBP WT, seven pairs; RBP DKO, seven pairs. (C) Time course of RRP emptying. Summary graph of integrated EPSC charge transfer as a function of time. EPSCs were triggered by maximal presynaptic depolarization as indicated in A. (D) Measurements of RRP recovery kinetics in RBP WT (Left) and RBP DKO synapses (Right). (Top) Presynaptic protocols used to deplete the RRP and to measure RRP recovery. Note that RRP recovery was measured at two time intervals: 0.2 and 1 s. (Bottom) EPSCs used to estimate RRP size and recovery. (E) RRP replenishment in ribbon synapses. (Top) Overlapping EPSCs showing RRP recovery dynamics for 0.2-s (Left) and 1-s (Right) intervals in representative RBP WT and DKO synapses. (Bottom) Normalized integrated responses as a function of time for the same experiment presented above. (F) Summary graphs of RRP recovery for 0.2-s and for 1-s time intervals. From Left to Right, the following parameters are displayed: EPSC amplitude recovery at 0.2-s intervals, EPSC charge recovery at 0.2-s intervals, EPSC amplitude recovery at 1-s intervals, and EPSC charge recovery at 1-s intervals. Number of experiments: RBP WT, five pairs; RBP DKO, five pairs. All summary graphs are mean ± SD. Statistical analyses were performed by either Student’s t test (B and F) or by ANOVA followed by a Bonferroni post hoc test (C), comparing RBP DKO with RBP WT. (*P < 0.05, and **P < 0.01; n.s., nonsignificant).