Chapter 3 - Biophysical Methods to Study Tight Junction Permeability

Abstract

Publisher Summary This chapter discusses the biophysical methods to study tight junction (TJ) permeability. The most common measure of TJ permeability to ions is the “transepithelial electrical resistance (TER).” TER although often serves as a rough indicator of tight junction permeability. Only more advanced biophysical methods like impedance spectroscopy and conductance scanning allow to quantify changes in paracellular resistance and to separate these changes from those occurring in transcellular or subcellular resistance. These techniques are thus superior to conventional TER measurements, which provide combined effects only. Tight junction permeabilities can be determined by flux or diffusion potential measurements. Biophysical measurements provide information about TJ channel properties such as pore size ion charge preferences and may help to identify independent and parallel pathways. For perturbing the TJ experimentally, different approaches are used, such as overexpression or knockdown of TJ proteins that can be achieved in in vitro models using cell cultures, while functional studies in vivo are usually performed in knockout (KO) animal models.