Voltage dependencies of <i>I</i>_Ca and [Ca²⁺]_i during EC coupling in hESC-CMs and hFVMs.

<p>A. <i>I</i>_Ca traces from typical hESC-CMs and hFVMs. <i>I</i>_Ca was evoked elicited using the voltage protocol depicted in the inset to the right. In brief, cells were slowly depolarized from the holding potential of −70 mV to −50 mV, where they were held to inactivate the Na⁺ current. Cells were then depolarized from −50 mV to test potentials ranging from −40 to +60 mV for 200 ms. B. Current-voltage relationships of <i>I</i>_Ca in hESC-CMs (red) and hFVMs (black). C. [Ca²⁺]_i transients evoked by <i>I</i>_Ca following depolarization to −40, 0, +40 mV in representative hESC-CMs and hFVMs. D. Voltage-dependence of the amplitude of the [Ca²⁺]_i transient in hESC-CMs and hFVMs. E. Voltage-dependence of the EC coupling gain factor in hESC-CMs and hFVMs.