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. 2001 May 15;98(11):6482–6487. doi: 10.1073/pnas.111447798

Figure 2.

Figure 2

GIRK2 and GIRK4 homomultimers are less sensitive than GIRK1/2 or GIRK1/4 to bupivacaine inhibition. Oocytes were injected with cRNA for Gβ1γ2 and the cRNA for GIRK1-GIRK2 dimer, GIRK2, or GIRK4. (a–c), Current responses were elicited by voltage steps to +50 and −100 mV in the absence and then presence of 500 μM bupivacaine (pH 7.5). I/Io is plotted as a function of bupivacaine concentration for GIRK1/2 (d), GIRK2 (e), and GIRK4 (f) at voltages ranging from −110 mV to −40 mV (VH = 0 mV). The smooth curves show the best fit to the Hill equation for −110 and −40 mV. For GIRK1/2, the Ki = 107 ± 14 μM (Hill coefficient h = 0.75 ± 0.06) at −40 mV and Ki = 71 ± 7 μM (h = 0.88 ± 0.03) at −110 mV. For GIRK2, the Ki = 500 ± 128 μM (h = 0.40 ± 0.05) and at −110 mV, the Ki = 825 ± 297 μM (h = 0.51 ± 0.07). For GIRK4, the Ki = 114 ± 26 μM (h = 0.28 ± 0.07) at −40 mV and Ki = 914 ± 394 μM (h = 0.39 ± 0.10) at −110 mV.