A role for a new vascular enzyme in the metabolism of xenobiotic amines

Although it has long been thought that environmental toxins may play an underlying role in vascular diseases such as atherosclerosis, this concept is not supported by any clear-cut experimental evidence of toxic metabolism by cardiovascular enzymes. In this study, we demonstrate that allylamine, a selective cardiovascular toxin in vivo, is actively metabolized in vitro by a purified vascular enzyme (semicarbazide-sensitive amine oxidase), which has been localized recently to vascular smooth muscle cells. Oxidative deamination of allylamine to a highly toxic aldehyde, acrolein, was blocked through enzyme inhibition by semicarbazide-sensitive amine oxidase inhibitors, which obviate allylamine's in vivo toxic manifestations. This unique demonstration of metabolism of a known in vivo cardiovascular toxin by semicarbazide-sensitive amine oxidase suggests that this vascular enzyme's physiological role may include metabolism of exogenous amines.