Metabolism of Nitrous Oxide by Human and Rat Intestinal Contents

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Abstract
N2O labeled with a stable heavy N isotope was used for in vitro studies of N2O metabolism in man and rat. At 5% O2 tension, which is comparable to normal O2 tension in the intestine in vivo, each gram of intestinal contents during a 16 h in vitro incubation produced 47 .+-. 13 nmol of molecular N for the rat and 103 .+-. 17 nmol for man. Active reductive metabolism of N2O by intestinal contents was significantly inhibited by antibiotics and by 20% O2 tension. Apparently the reduction of N2O to N may proceed through a single-electron transfer process with formation of free radicals. Metabolism of N2O could produce toxic intermediates, even though the end-metabolite is inert.