Solute—solvent coupling in epithelia: an electro-osmotic theory of fluid transfer

Abstract

An epithelial model has been studied in which the volume flow is almost entirely due to electro-osmotic coupling in the boundary membranes. The system gives rise to secretions which are isotonic to the distal bathing solutions under a range of conditions, and predicts that intracellular and lateral spaces play an important role in the overall flow process. The behaviour of an extracellular shunt has also been studied, and it appears that both the water and salt flow rate are dependent upon its magnitude and ion specificity. The model is proposed as an alternative to theories of local osmotic equilibration whose applicability to most epithelial systems is doubtful.