Figure 3.

Effect of ADP varies gradually with the ratio of WT to mutant SUR subunits. (A–H) MgADP responses of macroscopic currents recorded from Xenopus oocytes co-expressing Kir6.2 and the indicated mixtures of WT and mutant (DNN) SUR2A. (I) Average currents recorded in 300 μM ADP normalized to the current measured before in nucleotide-free solution. Numbers above bars indicate the number of patches included in the averages. Normalization was necessary because of the intrinsic variability of the oocyte system. The amplitudes in nA of the currents measured in 0 ATP before ADP application were on average (±s.e.m): 4.4 ± 0.6 (WT 1::0 DNN), 1 ± 0.5 (WT 0.8::0.2 DNN), 1.3 ± 0.4 (WT 0.6::0.4 DNN), 5.3 ± 1.4 (WT 0.5::0.5 DNN), 1.4 ± 0.4 (WT 0.4::0.6 DNN), 1.6 ± 0.7 (WT 0.2::0.8 DNN), 3.5 ± 1 (WT 0.16::0.84 DNN), and 1.5 ± 0.3(WT 0::1 DNN). This variability could not be attributed to a specific construct because experiments performed on the same day with the same batch of oocytes revealed no significant difference.