Low edge damage container insert that adjusts intestinal forceps biopsies into Ussing chamber systems

Ussing chamber experiments with human intestinal tissue are impeded by the small size of forceps biopsy specimens. Therefore, a miniaturized container insert featuring low edge damage was designed with an exposure area of only 0.05 cm2. It allows measurement of short-circuit current (ISC) and transmural resistance (Rt) on endoscopically obtained biopsy specimens, as well as alternating current impedance analysis and conductance scanning. Comparison with larger specimens mounted in a conventional Ussing chamber without the insert (exposure area 0.54 cm2) was made using rat jejunum and rectum. No differences in ISC, Rt, or secretory response were found, indicating proper sealing and prevention of edge damage, as well as tissue viability in the container system. If biopsy samples obtained from human rectum were mounted in the insert, the local resistance near the edge was almost the same as the overall resistance (52.3 Omega.cm2). Epithelial and subepithelial resistances of human rectum were 43+/-1 Omega.cm2 and 10+/-1 Omega.cm2, respectively. In conclusion, we present a tool that allows reliable Ussing-type, impedance, and conductance scanning measurements to be made from intestinal biopsy specimens.