Fig. 6.

W328M confers sensitivity to pentobarbital but not carisoprodol. A, in wild-type homomeric ρ1 receptors, neither pentobarbital (300 μM) nor carisoprodol (1 mM) enhanced GABA (EC₂₀)-gated current. In W328M mutant receptors, pentobarbital, but not carisoprodol, could enhance GABA-activated currents. The GABA EC₂₀ is denoted as control current amplitude. B, similar phenomenon existed with regard to direct-gating effects. In the W328M mutant receptors, pentobarbital could directly gate the channel to approximately 15% of the maximal current amplitude gated by GABA. In contrast, carisoprodol was ineffective in direct gating in either wild-type or W328M mutant receptors. Each data point represents the mean ± S.E. of four cells. Maximal GABA-gated current is denoted as 100%. *, significantly different from the wild-type response (p < 0.05).