Ion transport across the cecum in normal and colitic mice

This study was conducted to determine the ion transport mechanisms in the n ormal mouse cecum and compare them to an inbred mouse model of colitis. The Ussing chamber-voltage clamp technique was used to monitor the short circu it current (I-sc). The basal I-sc in the normal cecum was 82.6 +/- 5.8 mu A /cm(2). It was not affected by bumetanide, 9-anthracene carboxylate, amilor ide, and phenamil or by removal of Cl- ions; but was abolished by the remov al of Na+ ions. Flux measurements revealed the presence of neutral NaCl tra nsport. In the colitic cecum, the basal current was significantly higher th an the normal cecum, Basal current in the normal cecum was due primarily to Na+ absorption through a Na+ channel, while in the colitic cecum it was du e to Cl- ion secretion. cAMP addition in colitic cecum did not increase Cl- secretion, further suggesting that the tissue is already secreting at a ma ximal rate.