Measurement of R_m using voltage clamp pulses to determine the voltage-current (V-I) relationship.

<p>(A): Timing of onset of clamp pulses during different phases of the TNNP ventricle model AP are indicated by the stars. (B): Application of voltage clamp pulses 10 mV above (red curve) and below (blue curve) the membrane voltage at fifth point in the previous panel. (C): Membrane currents (Im) corresponding to clamp pulses in panel B. (D): V_m -I_m graph for the calculation of membrane resistance.