A Comparative Study of in vitro Metabolism of Histamine in Various Tissues from Domestic Animals (Cow, Sheep, Horse and Pig)

Abstract

AbstractPreviously, the in vivo metabolism of histamine in domestic animals has been examined. Ruminating and non‐ruminating species seemed to metabolize both parenterally and orally administered Hi in different ways. The present report is concerned with the ability of various tissues from the two types of animal to metabolize histamine. In all species kidney was the most active, and lung one of the least active histamine degrading tissues. In ruminating species, liver seemed to be the most active tissue next to kidney, while intestinal mucosa was of relatively minor importance. In the non‐ruminating species mucosa of the small intestine was the most active tissue after kidney, while liver was less active. Imidazoleacetic acid and an unidentified “metabolite XI” were the 2 main metabolites of histamine in most tissues examined, both at low and high substrate concentrations. The formation of “metabolite XI” was prevented by 10‐4 M aminoguanidine. Addition of S‐adenosylmethionine to the incubation mixtures in‐creased the inactivation rate of histamine in the lung of all species examined, in the intestinal mucosa of the ruminants and in the liver of the non‐ruminants. 1,4‐McH, did not seem to be oxidized to any extent in the methylating tissue.