Reversing the order of drug application yielded similar results. Superfusion of 44 mM ethanol significantly increased IPSP amplitude to 145 ± 7% of control (n = 5; F (2,4) = 69.14), and subsequent addition of 0.2 μM norBNI together with ethanol did not significantly affect IPSP amplitudes which remained at 148 ± 8% of control level (n = 5; Fig. 5B). The ethanol-elicited decrease of the paired-pulse ratio remained unchanged upon application of norBNI (63 ± 9% to 59 ± 12%, n = 5; not shown). Thus, norBNI prevented but did not reverse the action of ethanol on inhibitory transmission and there was no additive effect between ethanol and norBNI to increase GABA transmission, regardless of the order of drug application.
