FIGURE 6.

In the same cells, SUR1 modulates the activity of K_ATP channels but does not affect TRPM4 currents. A, continuous current traces in inside-out excised patches from representative cells cotransfected with Kir6.2 and SUR1 (K_ATP), Kir6.2, SUR1, and TRPM4 (K_ATP + TRPM4), or mock-transfected (GFP). V_m was first held at 0 mV, and patches were excised into K⁺ buffer (composition as in Fig. 5). Arrows mark the point of excision; dotted lines indicate zero current. Subsequently, V_m was stepped to +100 mV, and patches were exposed to Na⁺ buffer in absence or presence of 300 μm Ca²⁺ (composition as in Fig. 2). At selected times, the effect of 200 μm tolbutamide was tested. B, summary of steady-state currents (I_steady-state) measured in the conditions indicated on top of the data sets, from experiments as in A. Symbols represent data from individual patches (n = 5–12); bars indicate the means ± S.E. of all experiments. In columns 5 and 6, the same symbol is used to represent the currents in the absence (light gray) or presence (dark gray) of tolbutamide (tolb) from the same experiment. * and †, p < 0.05 as compared with the mock-transfected cells in 0 mV, K⁺ conditions, and in +100 mV, Na⁺, Ca²⁺ conditions, respectively (one-way analysis of variance and Kruskal-Wallis test).