Fig. 6.

The Notch1 intracellular domain (NICD) affects 4-aminopyridine (4-AP)-sensitive currents. A: whole cell voltage-gated K⁺ currents recorded in voltage clamp in a green fluorescent protein (GFP)-negative myocyte isolated from a wild-type (WT) mouse (MCM-WT) and a GFP-positive cell obtained from a transgenic mouse with NICD expression (MCM-NICD-GFP) before (Baseline) and after progressive exposure to 5 mM 4-AP. B: 4-AP-sensitive (Difference) current obtained by subtracting current traces before and after exposure to 4-AP shown in A. C: fitted curves of difference current traces shown in B with triexponential function (black curves) and relative monoexponential fitted components (shades of gray curves). D: quantitative data for the amplitude of Kv current components before (left) and after (right) exposure to 5 mM 4-AP for GFP-negative myocytes from MCM-WT mice (WT, n = 14; from 3 animals) and GFP-positive myocytes from MCM-NICD-GFP mice (NICD, n = 9; from 2 animals) are shown as means ± SE. *P < 0.05 vs. WT. E: quantitative data for the amplitude of 4-AP-sensitive (Difference) currents for myocytes reported in D. F: current-voltage (I–V) relations obtained by 10 s-depolarizing ramps from −110 to +80 mV. Data for MCM-WT mice (WT, n = 16; from 5 animals) and GFP-positive myocytes from MCM-NICD-GFP mice (NICD, n = 20; from 5 animals) are shown as means ± SE. Inward current at negative potential reflects inward rectifier K⁺ current.