The contribution of small gut to the 3-methylhistidine metabolism in the adult rat.

Twenty male adult Sprague-Dawley rats received parenteral nutrition following a duodenoileostomy which left only 8% to 10% of the small gut intact. On the first postoperative day, the urinary 3-methylhistidine (3-MH) excretion rose to 1.5 to 1.7 times the preoperative level but fell again within 12 to 14 days to the basal level. A control group of 10 rats with small gut anastomosis without resection yielded similar results. We conclude that, at least in rats, the small intestine does not make a significant contribution to 24-hour urinary excretion of 3-MH. The transient postoperative rise in 3-MH excretion is probably due to postinjury metabolism.