Fig. 5.

Block of NMDA EPSCs by toxin is similar in control cells (i.e., with both high and low P_rterminals contributing; A) or after 30 stimuli in 2 μm MK-801 (i.e., after most highP_r terminals have been masked;B). This suggests that both highP_r and low P_rterminals contain, on average, the same mix of presynaptic Ca²⁺ channel subtypes. A, B, The above experiment was performed by using 1 μm ω-CTx GVIA (ω-CTx). Each panel was obtained from a different cell. A similar protocol was used for 0.5 μm ω-Aga. C, Summary of experiments of the type shown in A andB. Error bars represent mean ± SEM. The amount of block by each toxin is not significantly different in control or after 30 stimuli in 2 μm MK-801.