[The effect of the small intestine on 3-methylhistidine metabolism in the human]

20 male adult Sprague-Dawley rats were fed exclusively parenterally. After achieving metabolic equilibrium they received a duodenoileostomy and subtotal resection leaving only 8-10% of the small gut. On the 1st postoperative day the urinary 3-MH excretion rose to 1.5-1.7 times the preoperative level, but on the 12th-14th postoperative day it fell again and was equal to the preoperative basal level. A control group of 10 rats undergoing a small gut anastomosis without resection yielded similar results. We conclude that the small gut source does not make a significant contribution to 24h-urinary 3-MH excretion in the adult rat. The transient postoperative increase in urinary 3-MH excretion is probably due to post-injury metabolism. In contrast to these are the measurements in two male patients with a short bowel syndrome because of an occlusion of the superior mesenteric artery. Both patients have a body weight of 60 kg, are aged 44 and 45 years respectively, and have a 24h-urinary 3-MH excretion of 120.7 +/- 28 mumol. More than 1 year after operation they are being nourished parenterally in metabolic equilibrium. The 24h-urinary 3-MH excretion in a similar control group of 8 healthy male volunteers is 229.4 +/- 25 mumol (measurements for 6 days after a 1-week meat-free diet). We conclude that the small gut source makes a significant contribution to 24h-urinary 3-MH excretion in the adult human. There is no evident correlation between the rat model and measurements in human.