Colonic epithelial ion transport is not affected in patients with diverticulosis

BACKGROUND: Colonic diverticular disease is a bothersome condition with an unresolved pathogenesis. It is unknown whether a neuroepithelial dysfunction is present. The aim of the study was two-fold; (1) to investigate colonic epithelial ion transport in patients with diverticulosis and (2) to adapt a miniaturized Modified Ussing Air-Suction (MUAS) chamber for colonic endoscopic biopsies. METHODS: Biopsies were obtained from the sigmoid part of the colon. 86 patients were included. All patients were referred for colonoscopy on suspicion of neoplasia and they were without pathological findings at colonoscopy (controls) except for diverticulosis in 22 (D-patients). Biopsies were mounted in MUAS chambers with an exposed area of 5 mm(2). Electrical responses to various stimulators and inhibitors of ion transport were investigated together with histological examination. The MUAS chamber was easy to use and reproducible data were obtained. RESULTS: Median basal short circuit current (SCC) was 43.8 μA·cm(-2 )(0.8 – 199) for controls and 59.3 μA·cm(-2 )(3.0 – 177.2) for D-patients. Slope conductance was 77.0 mS·cm(-2 )(18.6 – 204.0) equal to 13 Ω·cm(2 )for controls and 96.6 mS·cm(-2 )(8.4 – 191.4) equal to 10.3 Ω·cm(2 )for D-patients. Stimulation with serotonin, theophylline, forskolin and carbachol induced increases in SCC in a range of 4.9 – 18.6 μA·cm(-2), while inhibition with indomethacin, bumetanide, ouabain and amiloride decreased SCC in a range of 6.5 – 27.4 μA·cm(-2), and all with no significant differences between controls and D-patients. Histological examinations showed intact epithelium and lamina propria before and after mounting for both types of patients. CONCLUSION: We conclude that epithelial ion transport is not significantly altered in patients with diverticulosis and that the MUAS chamber can be adapted for studies of human colonic endoscopic biopsies.