REGULATION OF ELECTROLYTE TRANSPORT BY NITRIC-OXIDE IN THE MOUSE CECUM

The effect and role of nitric oxide (NO) in the regulation of ion tran sport in the mouse cecum were investigated. L-arginine, used to increa se NO production, increased short-circuit current (I-sc), a measure of ion transport, in a concentration-dependent manner with a maximal inc rease of 193.8 +/- 65.5 mu A/cm(2). This increase was not changed in C l-- or HCO3--free buffers, but was significantly decreased in Na+-free buffer. Using immunohistochemistry, the constitutive form of nitric o xide synthase was found not to be different in the inflamed cecum. The inducible form of the enzyme, however, which was absent in the cecum of normal mice, was present in high levels in the cecum of the colitic mouse. These results suggest that NO causes an increase in Na+ absorp tion. The increased levels of inducible NO synthase in the inflamed ce cum suggest a role for NO in the pathophysiology of inflammatory bowel disease. (C) 1998 Elsevier Science B.V. All rights reserved.