The metabolism and deamination of [14C]sulphamethazine in a germ-free pig: the influence of nitrate and nitrite.

Twenty-four hours after feeding nitrite in combination with [14C]sulphamethazine to a germ-free and a conventional control pig the level of [14C]desaminosulphamethazine in tissues from both pigs was high, accounting for 11 to 30% of the total tissue 14C. When another germ-free pig was fed [14C]sulphamethazine in combination with nitrate, a trace amount of [14C]desaminosulphamethazine was found by gas chromatography-mass spectroscopy in the skeletal muscle but not in other tissues. When a control pig was fed [14C]sulphamethazine and nitrate, [14C]desaminosulphamethazine was found in all tissues examined. The results from this study show that feeding pigs nitrite together with sulphamethazine increases the amount of desaminosulphamethazine in the tissues. Most of the desaminosulphamethazine found in the tissues of the control pig fed nitrate was presumably the secondary effect of bacterial reduction of nitrate to nitrite.