Figure 5
Representative calcium current recordings and IV traces from wt (A) and αMHC403/+ (B) ventricular myocytes, under control conditions (black lines) or the presence of ISO (red). Scatter plot with bar graphs show the cell capacitance (C) used to calculate ICa density (pA/pF) (D); and (E) the rate of inactivation (tau). Number of cells used for the study: wt n = 26, with ISO n = 13; αMHC403/+ n = 42, with ISO n = 22. (F) Representative Western blot images of CaV1.2 protein using total heart homogenates from wt (N = 5) and αMHC403/+ hearts (N = 4) repeated in triplicate. (G) In vitro PKA phosphorylated immunoprecipitated protein samples were used to fluorescently detect total phosphoprotein as well as PKA-specific phosphorylation. (H, I) Representative Fluo-4 calcium transients acquired on current clamped ventricular myocytes isolated from wt (H) and αMHC403/+ mice (I) under control conditions (black traces, n = 23, N = 5; and n = 18, N = 5 respectively) or the presence of 100 nM ISO (red traces, (n = 13, N = 5; and n = 11, N = 5 respectively). Scatter plots with bar graphs show relative amplitude (as F/F0, J), exponential rise time (ms) (K) and exponential decay (tau) (L). (M–N) Representative calcium current recordings from wt (M) and αMHC403/+ (N) cardiac myocytes under control condition (black) or the presence of 10 μM forskolin (blue). Scatter plot with bar graphs show ICa density (pA/pF) (O); and the rate of inactivation (tau) of ICa traces (P) presented as means ± SEM *p < 0.05 control versus ISO, or wt versus αMHC403/+, number of asterisks representing increasing significance in p value. Number of cells used: wt n = 30 ctrl, n = 6 with forskolin and αMHC403/+ n = 45 ctrl, n = 10 with forskolin.
