Curve-shift GIRK activation assay of D2R antagonism
upon coapplication of SV-III-130 and DA. A) Assay principles; 1 μM
DA elicits a full agonist response (left, red arrow). The subsequent
response amplitude in the presence of variable concentrations of SV-III-130
and DA, following 500 s coapplication (right, green arrow), was normalized
to the control response elicited by 1 μM DA. In the example
shown, 1 μM SV-III-130 coapplied with 100 μM DA; n = 3 oocytes. Thick lines represent mean normalized currents,
whereas thin lines indicate SEM. B) Current amplitude at the end of
the 500 s coapplication period, normalized to the instantaneous maximum
response amplitude in the same oocyte and plotted against DA concentration,
for varying concentrations of SV-III-130 or control. n = 3–7 oocytes per data point. Data shown are means ±
SEM.