Table 3.

Effects of exogenous H₂O₂ on normalized single-channel open and closed properties of recombinant Kir6.2/SUR1 and Kir6.2FL4A channels in intact HEK293 cells

	Kir6.2/SUR1			Kir6.2FL4A
Properties	H2O2	+5-HD	+SKF-7171A	H2O2
Open probability	4.30 ± 0.69†	3.47 ± 0.74*	0.91 ± 0.34	1.22 ± 0.45
Opening frequency	3.71 ± 0.53†	2.89 ± 0.58*	0.82 ± 0.36	1.09 ± 0.38
Mean open duration	1.13 ± 0.05*	1.25 ± 0.12	0.90 ± 0.16	1.09 ± 0.04
Mean closed duration	0.33 ± 0.04‡	0.35 ± 0.06†	1.71 ± 0.34	2.79 ± 1.84
Number of patches	11	5	5	6

Single-channel recordings of octameric Kir6.2/SUR1 and tetrameric Kir6.2FL4A channels expressed in transfected HEK293 cells were performed at −60 mV in symmetrical 140 mM K⁺ solutions in the cell-attached patch configuration. Application of H₂O₂ (1 mM) alone or coapplication of H₂O₂ together with the mitoK_ATP blocker 5-HD (100 μM) or the irreversible calmodulin antagonist SKF-7171A (10 μM) was achieved using a pressure-driven perfusion system. Single-channel properties were obtained as described in materials and methods. All values were normalized as described in Table 1 (control taken as 1) and averaged. Data are means ± SE.

^* P < 0.05;

^† P < 0.001;

^‡ P < 0.0001 (two-tailed, one-sample t-tests).