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 onl y 0.05 cm(2). It allows measurement of short-circuit current (I-SC) and tra nsmural resistance (R-t) on endoscopically obtained biopsy specimens, as we ll as alternating current impedance analysis and conductance scanning. Comp arison with larger specimens mounted in a conventional Ussing chamber witho ut the insert (exposure area 0.54 cm(2)) was made using rat jejunum and rec tum. No differences in I-SC, R-t, or secretory response were found, indicat ing proper sealing and prevention of edge damage, as well as tissue viabili ty in the container system. If biopsy samples obtained from human rectum we re mounted in the insert, the local resistance near the edge was almost the same as the overall resistance (52.3 Omega.cm(2)). Epithelial and subepith elial resistances of human rectum were 43 +/- 1 Omega.cm(2) and 10 +/- 1 Om ega.cm(2), respectively. In conclusion, we present a tool that allows relia ble Ussing-type, impedance, and conductance scanning measurements to be mad e from intestinal biopsy specimens.