Figure 7.

Effects of I_Na blockade on TA in a single isolated myocyte. (A) Submembrane Ca²⁺ transient threshold for TA versus g_Na in normokalemia (black) and hypokalemia (red). For most g_Na values, the Ca²⁺ threshold for TA is lower in hypokalemia than in normokalemia. (B) Voltage and Ca²⁺ traces for Ca²⁺ transients just above threshold with g_Na = 0, under normokalemic (black) and hypokalemic conditions (red). Due to the dynamical threshold automatically driving the voltage to the I_Ca,L threshold, we still can elicit a slow upstroke AP with complete I_Na block. To see this figure in color, go online.