Figure 8: Lack of agonist activity of MPC088 on PNs.

(a) Averages of 10 recordings from a PN exposed to multiple blue/UV light flashes, in the presence of cis-dominant MPC088 (30 μM) in the external solution, before (black) and after (red) the addition of gabazine (30 μM). There was no exogenous GABA present in the tissue. (b) Summary of results from eight experiments (eight PNs) including that described in a. The data indicate the magnitude of an outward current. The temporal sequence of illumination differed among the experiments (for example, only the cell in a received multiple blue/UV exposures), but the data plotted are the amplitudes from the blue to UV transition (in the case of the cell in a, this is the blue/UV transition from the first of the three exposures). Yellow-filled data points indicate results from the experiment in a. Each data point is the average obtained from four to ten consecutive recordings. The light-evoked membrane current was significantly reduced by gabazine (Wilcoxon signed-rank test, P=0.008). Error bars represent the s.e.m.