Fig. 3.
Characterization of VU0071063 activity against Kir6.2/SUR1 with patch-clamp electrophysiology. (A) Transfected cells expressing Kir6.2/SUR1 were voltage-clamped at −75 mV and stepped every 5 seconds to −120 mV to elicit inward current. Minor current run-up was observed following establishment of the whole-cell configuration and dialysis with the pipette solution. Addition of 1 or 30 μM VU0071063 led to rapid activation of inward current. (B) In contrast, addition of 50 mM diazoxide activated Kir6.2/SUR1 slowly. After achieving steady-state activation, addition of 50 μM VU0071063 led to further activation of Kir6.2/SUR1. Inward currents were blocked with 2 mM Ba2+. (C) Mean ± S.E.M. dose-response data fitted with 4-parameter logistic functions to derive EC50 values of 7 and 11 for VU0071063 (▪) and diazoxide (□), respectively (n = 5–10 per concentration). Data are normalized and expressed as percent (%) activation from baseline current in the absence of agonist.