Figure 3.

Effects of Gd³⁺ on the compressibility (A) and surface potential (B) of monolayers made of DMPS and DMPC. In B, surface potential traces are shown only for control and 10⁻⁵ M Gd³⁺, the latter essentially coincided with curves for 10⁻⁶ and 10⁻⁴ Gd³⁺. In all measurements the subphase electrolyte contained 10 mM KCl, 1 mM 2-(N-morpholino)ethanesulfonic acid buffer, pH 7.0. Coding of the traces is given in B. The inset in A represents the effect of 10 μM Ca²⁺ on the DMPS monolayer in the same background electrolyte.