Feline endotoxin shock: effects on tissue histamine and histidine decarboxylase activity

Tissue histamine levels as well as specific and non-specific histidine decarboxylase were examined before and at various times (5 and 10 min) after the intravenous injection of a lethal dose (2 mg kg-1) of E. coli endotoxin in anaesthetized cats. Histamine levels were increased 5 min after endotoxin, especially in the skin, liver, lung and stomach. There was evidence, in most of the cats, for a rapid and substantial activation of specific histidine decarboxylase especially in the lungs, liver, heart and gastrointestinal tract 5-10 min after endotoxin administration. It is suggested that endotoxin induces the local formation of histamine and that this formation and local release may contribute to the pathophysiology of endotoxin shock in this species.