A non-linear mathematical model representing the consequence of voltage decrement in the transverse tubular system on the measured conductance-voltage curve for the inward rectifier in frog skeletal muscle

The inwardly rectifying potassium conductance in frog skeletal muscle resides largely in the transverse tubular system (TTS). In voltage-clamp experiments, the membrane potential of the TTS will in general not be the same as the surface potential, owing to voltage drop across the tubular luminal resistance; hence the measured total conductance-voltage relation is liable to differ from the intrinsic rectifying function.