Metabolism of injected [14C] histamine in the kidney of the dog.

In experiments on anaesthetized dogs, [(14)C]histamine was given in a steady infusion into one of the renal arteries, while urine was collected from both kidneys separately. The kidney which received the intra-arterial injection of [(14)C]histamine excreted several times more [(14)C]-labelled methylhistamine, methylimidazoleacetic acid and imidazoleacetic acid than did the other kidney, indicating that histamine may be inactivated in the canine kidney not only by histaminase but also by the histamine methylating enzyme.