Xylose catabolism in the experimental rat blind loop syndrome: Studies, including use of a newly developed d-[14C]xylose breath test

Abstract

Intraluminal bacterial catabolism of xylose in an experimental rat blind loop model has been evaluated by means of a newly developed d-[14C]xylose breath test. The system employed affords frequent determination of total CO2 and 14CO2 and the opportunity for post-therapy evaluation. Rats with jejunal self-filling blind loops expired 40% of an orogastric dose of d-[14C]xylose as 14CO2 over 6 hr, as compared to 9% in nonoperated control rats and 17% in surgical controls with self-emptying blind loops. 14CO2 production decreased significantly with neomycin treatment of rats with self-filling blind loops, and was correlated with a significant decrease of gram-negative coliforms in jejunal contents. Small intestinal bacteria could be implicated in the production of up to 76% of the 14CO2 production by blind loop rats, with colon bacterial catabolism of unabsorbed xylose a smaller additive factor.Intravenous administration of d-[14C]xylose demonstrated that 14CO2 production by cellular metabolism of xylose was an insignificant part of the breath 14CO2 output. Urinary xylose excretion was significantly decreased in rats with self-filling blind loops by an amount correlating with the demonstrated intraluminal bacterial catabolism of xylose. Thus, intraluminal catabolism of xylose by small intestine bacteria appears to be the major determinant of the decreased urinary xylose excretion of the experimental blind loop syndrome, with colon bacterial catabolism of malabsorbed xylose a probable minor additional factor.