Fig. 5.
Current density-voltage (I–V) curves of voltage-gated Na+ current (INa; A) and L-type Ca2+ current (ICa; B). A,a and B,a: I–V relationships in control (black) and during carvedilol treatment (gray). Means ± SE. A,b and B,b: family of current traces at all test voltages in control (Ctrl; black) and during carvedilol treatment (gray) recorded from same cell. The following voltage-clamp protocols were used. ICa, holding potential (VH) = −80 mV; depolarization to −50 mV, followed by 350-ms depolarization steps in increments of 10 mV to a maximum depolarization of +60 mV. INa, VH = −80 mV; 30-ms voltage steps −80 to +30 mV in 5-mV increments. INa, n = 8 (carvedilol, 1 µM), *P < 0.03; ICa, n = 5 (carvedilol, 10 µM), *P < 0.04 (ANOVA).