Figure 6. Spontaneous inward current is carried by Ca²⁺ ions in whole-cell and outside-out patches.

A, effect of replacement of 126 mm NaCl by 89 mm CaCl₂ on spontaneous whole-cell current. B, mean I–V relationship of spontaneous whole-cell current in 89 mm CaCl₂ in five cells. C, single-channel currents in 1.5 mm and 89 mm CaCl₂ in the same outside-out patch. D, mean I–V relationship of unitary current in five outside-out patches in 89 mm CaCl₂.