Allylamine cardiovascular toxicity: evidence for aberrant vasoreactivity in rats

Allylamine (AA, 3-aminopropene) is a specific cardiovascular toxin used experimentally to model myocardial necrosis and atherosclerosis. In these physiologic experiments, 10-day AA exposure (100 mg . kg-1 . day-1 by gavage) produced severe myocardial necrosis and increased heart rate but did not affect systolic blood pressure in rats. Mid-thoracic aortic ring segments were removed, and reactivity to contractile and relaxant agonists was tested. Aortic rings (approximately 3 mm) from AA-treated rats were contracted significantly more by high potassium (100 mM) and slightly more by norepinephrine (NE, 10 microM) than anatomically matched control aortic rings. No difference in aortic ring NE sensitivity or percentage relaxation in response to acetylcholine (1 microM) or sodium nitroprusside (100 microM) was detected between control and AA-treated rat aortic rings. Allylamine (1 microM-1 mM) induced modest, concentration-dependent contractions and tension oscillations in aortic rings from both control and AA-treated rats. Aortic rings from AA-treated rats, however, were more sensitive to AA. Vascular smooth muscle cells derived from control and AA-treated rat aortas had similar toxic sensitivity to AA in vitro using the MTT viability assay. The mechanisms by which AA exposure increased heart rate in vivo and contractility of aortic rings are unknown. These experiments support the previously proposed concept that AA-induced acute myocardial necrosis is due to coronary vasospasm and myocardial ischemia and cell injury.