Figure 2. Effect of pentobarbital on basal (unstimulated), isoproterenol-stimulated (1 micro Meter) and forskolin-stimulated (25 micro Meter) cyclic adenosine monophosphate accumulation in cultures of cortical neurons. Samples were exposed to 0.5 mM 3-isobutyl-1-methylxanthine and the indicated concentration of pentobarbital for a 20 min preincubation period before the addition of isoproterenol or forskolin. Results are presented as the mean+/- SEM values for 8-12 experiments. *P < 0.05 and **P < 0.01 compared to the value in the presence of isoproterenol or forskolin, but in the absence of pentobarbital by analysis of variance and post hoc test using the Dunnett's test.