Ileal mucosal growth during intraluminal infusion of ethylamine or putrescine

Either ethylamine or the diamine putrescine was infused at the rate of 1 mumol/h for 66 h into the ileal lumen of rats. Total mucosal RNA, DNA, and protein content was greater in amine-treated rats than in rats receiving 0.9% NaCl. Growth was greatest in the mucosa surrounding the tip of the infusion catheter but was also observed 9 cm proximal and distal to the catheter tip. Infusion of these amines induced the activity of the enzymes ornithine and S-adenosylmethionine decarboxylase. Ornithine decarboxylase activity was increased 2- and 6-fold and S-adenosylmethionine decarboxylase activity 10- and 5-fold by putrescine and ethylamine, respectively. Induction of the polyamine biosynthetic enzymes was not accompanied by increases in the tissue content of polyamines. Putrescine, spermidine, and spermine content of the ileal mucosa surrounding the catheter tip was the same in 0.9% NaCl-, ethylamine-, and putrescine-treated animals. Finally, ethylamine was without effect on serum gastrin concentration in these experiments. The results suggest that amines regulate mucosal growth and may do so by modulating the activity of the enzymes involved in the synthesis of the polyamines.