Figure 4. Effect of pentobarbital on cyclic adenosine monophosphate accumulation in the presence and absence (basal) of 1 micro Meter isoproterenol-stimulated in cortical slices from rat brain. 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 vehicle control. Data are presented as percent change in cyclic adenosine monophosphate accumulation in the presence of pentobarbital compared with the response in the absence of the pentobarbital and represent the mean+/-SEM values for 8-12 experiments. *P < 0.05 compared to control value in the absence of pentobarbital by a one-sample t test corrected for multiple comparisons. Inset: Control values for cyclic adenosine monophosphate production in the absence and presence of 1 micro Meter isoproterenol. Data are presented as the mean+/-SEM values for 12 experiments. **P < 0.02 compared to value in the absence of isoproterenol by a paired Student's t test.