Histamine Formation and Catabolism in the Faeces with Special Reference to Dystrophia Myotonica

Abstract

Faeces from patients with dystrophia myotonica and controls were incubated aerobically for 20-24 hours with L-histidine, L-carnosine, histamine diphosphate, N-acetylhistamine, and N-acetyl-L-histidine. Whereas inherent histamine-like activity is stable in faeces from patients with dystrophia myotonica, histamine added to faeces with inherent histamine-like activity is degraded, although to a lesser degree than histamine added to patient faeces with low inherent histamine-like activity or to control faeces. N-acetylhistamine is degraded in both control and patient faeces and a bioactive substance appears that seems to be identical with free histamine. N-acetyl-L-histidine also seems to be catabolized to free histamine in patient faeces. In patient faeces with high inherent histamine-like activity, L-histidine is converted to histamine to a greater proportion than to urocanic acid and dihydrourocanic acid. The latter metabolites are prominent in control faeces, whereas only minute amounts of histamine are formed. On prolonged incubation, however, ample amounts of histamine are formed, and then the stability of Chistamine added to control faeces seems to increase. L-carnosine is also converted to a biologically active substance. In dystrophia myotonica increased formation seems to be the main cause of the high inherent faecal histamine-like activity.