A 1H-NMR investigation of the mechanism for the ionophore activity of the bile salts in phospholipid vesicular membranes and the effect of cholesterol.

A 1H-NMR method previously applied to ionophore-medicated transport is used to investigate a similar behaviour by the bile salts. The permeability of phosphatidylcholine vesicles to Pr3+ is increased by several orders of magnitude over the self-diffusion rate and the kinetics indicate a transbilayer movement of inverted micelles [Pr(bile salt)4]. In vesicles containing 40 mol% cholesterol the mechanism of permeability is radically altered and the di- and trihydroxy bile salts behave differently.