INTERPRETATION OF PASSIVE PERMEABILITY MEASUREMENTS ON LIPID-BILAYER VESICLES - EFFECT OF FLUCTUATIONS

A stochastic model for migration dynamics of solute molecules from the bulk aqueous phase to the intravesicular water pool is developed with a goal to interpret recent passive permeability measurements of bilay er membranes. Previously neglected fluctuations of the number of solub ilized species in the inner water pool of a vesicle are naturally inco rporated into the model. For a homogeneous one-phase bilayer, the mode l predicts exponential long-time asymptotics of the migration dynamics with a rate constant given by a sum of the frequencies of exit and en try of a solute molecule from/into the intravesicular water pool into/ from the bulk aqueous phase. The long-time constant is directly relate d to the membrane permeability. (C) 1997 Elsevier Science B.V.