Increased concentrations of
reactive oxygen species in children with depleted
antioxidant defences have been implicated in a cycle of
malnutrition, malabsorption, and
infection leading to protracted diarrhoea. A rat model of chronic
vitamin E deficiency has been used to study the effects of
antioxidant depletion on jejunal structure and function in vitro. Basal intestinal short circuit current (Isc), a measure of net electrogenic ion movement across the intestinal epithelium, was greater in chronically
vitamin E deficient jejuna than controls, as was the electrogenic secretory response to
aminophylline and Escherichia coli STa but not to
bethanechol. The
galactose stimulated current was also greater in
vitamin E deficient jejuna. Indices of lipid peroxidation (concentrations of
thiobarbituric acid reactive substances and
malondialdehyde) were increased in the
vitamin E deficient small bowel. Small intestinal brush border membranes from
vitamin E deficient animals displayed changes in both static and dynamic components of membrane fluidity measured by steady state fluorescence polarography. The results of these studies support the hypothesis that oxidative stress in subjects with compromised
antioxidant defences results in small intestinal hypersecretion, which could predispose to or perpetuate protracted diarrhoea.