Amine oxidase in human blood vessels and non-vascular smooth muscle

The pattern of amine oxidation was studied in human blood vessels at various stages of development, and in tissues with muscular layers made up predominantly or exclusively of smooth muscle. Specific activity of benzylamine oxidase, present in all vascular tissues examined, was higher in vessels than in other tissue; the enzyme, in organs rich in non-vascular smooth muscle, though lower than in blood vessels, was significantly higher than in striated muscle or connective tissue. The localization of benzylamine oxidase activity in smooth muscle, as opposed to connective tissue, may have important physiological implications.