Recording of Na⁺/Ca²⁺ exchanger current (I_NCX) in rat ventricular myocytes.

<p>(A) Voltage protocol used for measuring I_NCX, the typical membrane currents obtained in a myocyte in the absence (a) or presence 5 mM Ni²⁺ (b). Currents were elicited by ramp pulse from +80 mV to −120 mV at a rate of 90 mV/s. (B) Current–voltage (I-V) relationship before (a) and after (b) application of 5 mM Ni²⁺. (C) I-V relationship for I_NCX (a–b).