Release of intestinal diamine oxidase by histamine in rats.
Diamine oxidase activity was measured in the intestinal mucosa, lymph, and in the serum of rats, to determine whether histamine, a substrate of diamine oxidase, liberates this enzyme from its mucosal storage site(s). Histamine induced a sharp rise in intestinal lymph flow, lymph protein, and lymph diamine oxidase, lasting less than 1 h after the histamine injection. The rise in lymph diamine oxidase activity was dose dependent over a narrow concentration range (0.05-0.2 mmol/kg, i.v. and 0.15-0.6 mmol/kg i.d.). It did not correlate with the dose dependent increase in lymph flow or lymph protein. A single maximal intraduodenal dose of histamine caused a 41.6-fold increase in the lymph diamine oxidase activity and a 2.4-fold increase in the serum enzyme level temporarily. A second injection of histamine, 2 h after the first, resulted in a comparatively smaller increase in the lymph enzyme. The extent of the reduction was dependent on the magnitude of the first injection. The results suggest that histamine causes a limited liberation of diamine oxidase from the intestinal mucosa. The function of this enzyme release may be a protective response by the mucosa to reduce toxic levels of free histamine, either liberated by the mucosal tissue or absorbed from the intestinal lumen.
D006631:Amine Oxidase (Copper-Containing) / Q000378:metabolism*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D006493:Heparin / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology*; D007422:Intestines / Q000201:enzymology*; D008196:Lymph / Q000201:enzymology; D011506:Proteins / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains
D011506:Proteins; D006632:Histamine; D006493:Heparin; D006631:Amine Oxidase (Copper-Containing)