Figure 4. Stereoselective effects of the barbiturate enantiomers in potentiating the current induced by 1 [micro sign]M GABA: (A) Hexobarbital. (B) Pentobarbital. (C) Thiopental. The data points represent the mean potentiations from an average of 6, 12, and 18 cells, respectively, and the error bars are standard errors in the mean. If an error bar is not shown, it would be smaller than the size of the symbol.