Potentiometric-scanning ion conductance microscopy for measurement at tight junctions

Abstract

Scanning Ion Conductance Microscopy (SICM) has been developed originally for high-resolution imaging of topographic features. Recently, we have described a hybrid voltage scanning mode of SICM, termed Potentiometric-SICM (P-SICM) for recording transmembrane ionic conductance at specific nanostructures of synthetic and biological interfaces. With this technique, paracellular conductance through tight junctions – a subcellular structure that has been difficult to interrogate previously – has been realized. P-SICM utilizes a dual-barrel pipet to differentiate paracellular from transcellular transport processes with nanoscale spatial resolution. The unique combination of voltage scanning and topographic imaging enables P-SICM to capture paracellular conductance within a nominal radius of several hundred nanometers. This review summarizes recent advances in paracellular conductance recording with an emphasis on the P-SICM based approach, which is applied to detect claudin-2 mediated permeability changes at the tight junction.

Keywords: :

• tight junction
• claudin
• ion channel
• SICM
• patch clamp
• epithelium

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgment

This work is supported by the grants from the National Institutes of Health (NIDDK 1R21DK082990), the Research Corporation for Scientific Advancement, and the American Heart Association to L.A.B. and from the National Institutes of Health (grants R01DK084059 and P30 DK079333) and American Heart Association (grant 0930050N) to J.H.