Fig. 3.

Modulation by intracellular free Mg²⁺ concentration ([Mg²⁺]) of the outward component of the whole cell I-V relationship in HEL cells. A: cell suspended in 149 Na⁺/5 mM K⁺ solution (solution 9) was whole cell patch-clamped with a KCl-based internal solution (solution 1) supplemented with 1 mM Mg²⁺. The 200-ms voltage-ramp protocol administered every 3 s is shown in B. Magnitude of the outward current at +90 mV was extracted from ramp data and plotted as a function of time. B: I-V relationships immediately after whole cell configuration was attained (episode 1) and 339 s later (episode 114) in experiment presented in A. C: cell was whole cell patch-clamped with a nominally Mg²⁺-free KCl-based internal solution (solution 1). The 200-ms voltage-ramp protocol is shown in D. Magnitude of the outward current at +90 mV was extracted from ramp data and plotted as a function of time. D: I-V relationships corresponding to episodes 26, 88, and 137 after whole cell configuration was attained in experiment presented in C.