Figure 4. Effect of Ro 31-8220 on glutamate release evoked by 4-aminopyridine in the absence or presence of halothane. Synaptosomes were preincubated with various concentrations of Ro 31-8220, a selective inhibitor of protein kinase C, in the absence (circles) or presence (squares) of 0.9 mM halothane. Glutamate release was evoked with 1 mM 4-aminopyridine. The data are averages of two independent experiments (ranges less than 10%).