Fig. 3.

The Notch1 intracellular domain (NICD) reduces fast Na⁺ current (I_Na) in adult myocytes. A: whole cell voltage-gated I_Na 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 consisted of a family of depolarizing steps in 5-mV increments. B: current-voltage (I–V) relations, voltage dependency of conductance, steady-state activation, steady inactivation, and time dependency of reactivation for I_Na in GFP-negative myocytes from MCM-WT mice (WT, n = 14–16; from 3 animals) and GFP-positive myocytes from MCM-NICD-GFP mice (NICD, n = 11–14; from 4 animals) are shown as means ± SE. g_max, maximal conductance. *P < 0.05 vs. WT. Fitting parameters are shown in Table 2.