Fig. 4.

The Notch1 intracellular domain (NICD) reduces Kv current components of adult myocytes. 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). The voltage-clamp protocol consisting of a 25 s-depolarizing step is shown at the bottom. B: fitted curves of current traces shown in A with multiexponential function (black curves) and monoexponential fitted components (shades of gray curves). For the MCM-NICD-GFP myocyte, a biexponential function was used because this cell lacked transiet outward K+ current (I_to). C: quantitative data for the amplitude of Kv current components in GFP-negative myocytes from MCM-WT mice (WT, n = 17; from 3 animals), GFP-positive myocytes from a MCM-GFP mouse (GFP, n = 11), and GFP-positive myocytes from MCM-NICD-GFP mice (NICD, n = 18; from 4 animals) are shown as means ± SE. I_to, K⁺ currents with rapid activation; I_K,slow1 and I_K,slow2, intermediate and slow kinetics of inactivation; I_ss, sustained (noninactivating) component. *P < 0.05 vs. WT; **P < 0.05 vs. GFP.