Figure 1. Representative voltage clamp traces of Xenopus oocytes exposed to various combinations of ketamine and benzethonium chloride (BCl). Each trace is from a different cell. All cells were voltage clamped at -70 mV, and the agonist was 10 sup -7 M acetyl-beta-methylcholine in each instance. Ketamine concentrations were chosen to reflect approximately the median inhibitory concentration of the racemic mixture, and BCl concentrations were those present in 50 micro Meter Ketalar. Bath solutions were (A) control (Tyrode's solution), 4.8 micro Coulomb;(B) S(+) ketamine (50 micro Meter), 3.1 micro Coulomb;(C) R(-) ketamine (50 micro Meter), 2.4 micro Coulomb;(D) equimolar S(+)/R(-) ketamine (50 micro Meter), 1.3 micro Coulomb;(E) BCl (0.3 micro Meter), 3.3 micro Coulomb;(F) equimolar S(+)/R(-) ketamine (50 micro Meter) plus BCl 0.3 micro Meter), 0.8 micro Coulomb; and (G) Ketalar (50 micro Meter), 0.5 micro Coulomb.