Fig. 5.
βAR-mediated ICa enhancement is blunted by reducing dynamic channel insertion. (A) Whole-cell currents elicited from a representative AMVM during a 300-ms depolarization step from −40 mV to 0 mV before (control: black) and during application of 100 nM ISO (blue). (B) I-V plot summarizing the results from n = 7 cells (from n = 7 animals) subjected to test potentials ranging from −50 mV to +100 mV. Currents were normalized to cell capacitance to generate current density. (C) Voltage-dependence of the normalized conductance (G/Gmax) before and during ISO application, fit with Boltzmann functions. (D–F) Whole-cell currents (D), I-V (E), and G/Gmax plots (F) from AMVMs pretreated for 2 h with 10 μM nocodazole (n = 4, n = 7). (G, H) The same for cells treated with 5 μM lat-A (n = 5, n = 5). (J–L) Results from cells treated with a combination of both (n = 3, n = 6).