Figure 4.

Voltage clamp study indicating that RNS60 increases transmitter release without modifying calcium current or its relationship with transmitter release. (A) Set of traces recorded in Control ASW show the amplitude and time course of the presynaptic calcium current (black), the amplitude and time course of the postsynaptic response (green) elicited by the rapid voltage clamp step shown in the third trace (Pre Dep, black). (B) Set of traces recorded in RNS60 ASW with the same amplitude depolarizing pulses as in the control set; EPSPs are red. (C) Superposition of calcium currents (upper traces) and EPSPs (lower trace) from panel (A) for control (green) and panel (B) for RNS60 (red) ASW demonstrates that there was no change in the time course or amplitude of the presynaptic calcium current, but a clear increase in the EPSP amplitude in RNS60 compared to control ASW. (D) Plot of EPSP amplitude as a function of presynaptic depolarization step for the five synapses. (Set of recordings from each synapse use the same marker.) The oxygenated control is modified from Figure 3B in (Llinas et al., 1981b) and provides data from seven synapses superfused with control ASW oxygenated with a 99.5% 02 and 0.5% CO₂ gas mixture or with 0.001% H₂O₂. (E) Mean EPSP and s.e.m. as a function of mean presynaptic depolarizations for synapses in panel (D). Oxygenated control is mean of data in Figure 3B in (Llinas et al., 1981b). [^*T_{(4, 8)} = 4.27, p < 0.01; ^**T_{(4, 8)} = 5.1, p < 0.001; ^***T_{(4, 8)} = 3.54, p < 0.05, t-test].