A, Representative traces showing whole cell currents activated by an EC30 concentration of GABA (5 μM) in HEK293 cells stably expressing α1β2γ2GABAA receptors. Efavirenz was co-applied with GABA for 10 sec. Note that ARV drug-induced action was rapid and reversible. B, Summary data of the modulatory effect induced by ZDV, FTC and NVP (30 μM). All currents were normalized to the GABA control response (GABA alone). *P < 0.05, paired t-test, compared to the control, n=6–8. Data are presented as means ± SEM.