Implications of a non-lamellar lipid phase for the tight junction stability. Part II: Reversible modulation of transepithelial resistance in high and low resistance MDCK-cells by basic amino acids, Ca2+, protamine and protons.

The transepithelial resistance of confluent epithelial cell monolayers was monitored to investigate the influence of basic amino acids, Ca2+, protamine and protons on tight junction electrical resistance. In an accompanying paper we investigated the effect of these substances on the lamellar/hexagonal II phase transition in reconstituted phospholipid membranes containing phosphatidylserine and phosphatidylethanolamine. We conclude that the permeability of tight junctions may be described by a lipid phase equilibrium where the lamellar phase corresponds to an open state and the hexagonal lipid phase to the closed state of the cell contact. This dynamic lipid model is well suited to describe the morphological as well as functional properties of the tight junctions.