The flux-ratio equation under nonstationary boundary conditions

Abstract

Ussing's equation for the ratio of undirectional tracer fluxes, passing in opposite directions through a membrane which has transport properties varying with the distance from a boundary, has recently been extended to include nonstationary fluxes under stationary boundary conditions [Sten-Knudsen and Ussing, J. Membrane Biol. 63:233–242 (1981)]. Using a concise and more generally valid method of proof, that extension is generalized further to include nonstationary boundary values of the tracer concentrations, and to obtain new results useful in the design of experiments.