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. 1997 Aug 15;17(16):6075–6085. doi: 10.1523/JNEUROSCI.17-16-06075.1997

Fig. 2.

Fig. 2.

Glycinergic IPSCs and single-channel events in RGCs. A, Representative traces of glycinergic IPSCs recorded at −80 mV under symmetrical Cl−conditions. The inset in the lowest paneldisplays at an expanded time scale a section on the decay phase of an IPSC in which discrete current fluctuations, corresponding to the opening and closing of single channels, are clearly detected. The predominant amplitude of the elementary currents was ∼4–5 pA at −80 mV, corresponding to a single-channel conductance of ∼50 pS.B, Display of the IPSCs amplitude distribution for the same cell. The IPSC histogram (bin width, 7 pA) contains 638 events, with a mean amplitude of 80 pA. The solid linecorresponds to the fit of the data by a single gaussian function; fit parameters were a mean of 60 pA and SD of 30 pA. A relatively high detection threshold (15 pA) was used in the analysis to avoid including single-channel events. The scaled noise distribution (1000 events; bin width, 0.7 pA) is displayed in black. C, The upper panel shows single-channel events elicited at −100 mV by bath-applied glycine (50 μm). The left plot in the lower panel illustrates an all-point histogram from the same experiment in which two channels with the same elementary current can be identified (6 sec recording; bin width, 0.2 pA; the leak current has been subtracted for clarity). The solid lines correspond to the fit of the data by three gaussian functions; fit parameters (mean ± SD, in pA) for each gaussian were 0.02 ± 0.04, −5.5 ± 0.7, and −10.8 ± 0.9. Theright lower panel displays the I–Vrelation for the elementary glycine-activated current determined from all-point histograms at three different membrane potentials; thesolid line corresponds to the fit of the data by a linear function, yielding an estimated single-channel conductance of 55 pS. D, Glycinergic synaptic activity is displayed as the sum of the amplitudes of all IPSCs detected during 20 sec intervals as a function of time. The addition of the GABAA antagonist SR95531 (b) did not affect synaptic activity, whereas strychnine at 0.3 μm (c) exerted a profound block on IPSCs and eliminated synaptic activity at 2 μm (d). Holding potential, −60 mV.