Effect of the GABAρ
receptor antagonist TPMPA on the GABA-elicited currents modulated
by DA. (A) Sample records showing that TPMPA effectively and reversibly
blocked the currents generated by 3.5 μM GABA and those modulated
by 105, 210, and 750 μM DA. Note that the coapplication of DA
concentration, higher than 105 μM, and TPMPA enhanced the inhibitory
effect. (B) TPMPA antagonism on currents elicited by coapplication
of GABA and either DA at 105, 210, and 750 μM. Data points are
the means ± SEM from 6 oocytes (n = 6) from
5 frogs (N = 3).