Novel modified Ussing chamber for the study of absorption and secretion in human endoscopic biopsies

The aim of this study was to design and evaluate a modified Ussing chamber, that makes use of constant air suction (modified Ussing air suction chamber, MUAS) for fixation of biopsy specimens. Standard size forceps biopsies were taken from the descending part of duodenum from patients undergoing endoscopy. Short circuit current (SCC) and conductance (G) were measured during basal conditions and after addition of different sugars and secretagogues. Histologic examination was performed to determine the degree of tissue damage after study in the chamber. Basal SCC was 54.7 +/- 4.3 microA x cm(-2) and G was 58.7 +/- 4.7 mS x cm(-2) (mean +/- SEM, n=48) and steady values of these parameters were observed for at least 2 h. Reproducible and steady responses in SCC were obtained with D-glucose (SCCmax=172 +/- 22.1 microA x cm(-2); EC50=6.9 +/- 0.7 mM, n=5) and D-galactose (SCCmax=233 +/- 55.7 microA x cm(-2); EC50=9.2 +/- 0.7 mM, n=3), and secretory responses with 5-hydroxytryptamine, 100 microM (DeltaSCC= 16.1 +/- 3.8 microA x cm(-2), n=10), histamine, 100 microM (DeltaSCC=24.0 +/- 4.1 microA x cm(-2), n=10) and prostaglandin E2, 1 microM (DeltaSCC=30.3 +/- 5.4 microA x cm(-2), n=6). Experimental biopsy specimens showed intact surface epithelium by histologic examination and did not differ from controls apart from minor indications of edge damage. No difference in basal electrical parameters and D-glucose fluxes were found between Helicobacter pylori positive and negative patients. Our data suggests that the MUAS chamber represents a promising alternative approach to measure transport processes in intestinal endoscopic biopsies.