Figure 4. Differential effects of 30 μm picrotoxin on unitary currents evoked by glycine in neonatal and juvenile rats.

Point-per-point amplitude histograms of single-channel currents evoked by 30 μm glycine alone (A1 and B1) and in the presence of 30 μm picrotoxin (A2 and B2) in neonatal (A1 and A2) and juvenile rats (B1 and B2). Amplitude histograms were obtained from 50 s recordings in each condition (bin width / 0.1 pA). Example traces of each recording are illustrated in the insets (2 kHz cut-off frequency; V_H = −70 mV). Note that in the presence of 30 μm picrotoxin, the unitary conductance of the GlyR was decreased from 54 to 40 pS in the patch excised from a P22 rat (B1 and B2). Currents larger than 5 pA in histogram B2 correspond to superimposed openings as shown in the inset.