Fig. 1. Effects of propofol and 4-iodopropofol on GABAAreceptors. The effects of propofol and 4-iodopropofol were tested on recombinant human GABAAα1β2γ2receptors expressed in HEK 293 cells using whole-cell patch clamp recording. (A ) Representative recordings demonstrating direct activation and potentiation of GABA responses at the EC20(12 μm) for GABA by propofol (left ) and 4-iodopropofol (right ). (B , Left ) Concentration–effect curves for potentiation of GABA responses at the EC20(12 μm) for GABA by propofol (circles) and 4-iodopropofol (squares). (Right ) Concentration–effect curves for direct activation of GABAAreceptors by propofol (circles) and 4-iodopropofol (squares). Data shown as mean ± SEM.