Diffusion of K+, Cs+ and quinine+ through tight junctions among taste bud cells

Although tight junctions among taste bud cells (TBCs, animal chemical sensors) prevent the diffusion of food constituents to protect TBCs, these tight junctions are suggested to permeate some food constituents in order to elicit taste responses to them. In this study, we quantitatively investigated the ionic diffusion through these tight junctions. Here, we show that they are slightly permeable to small ions and that their permeability contributes to taste responses only when permeating ions have potent pharmacological effects. We discuss the role of tight junctions in taste reception and the contribution of tight junctions in engineering artificial chemical sensors.