Amiodarona causa vasodilatação dependente do endotélio em artérias coronárias caninas

Abstract

ObjectiveTo assess the vasodilating effects of amiodarone on canine coronary arteries by using solutions of amiodarone dissolved in polysorbate 80 or water. MethodsRings of coronary arteries, with or without intact endothelium, were immersed in Krebs solution and connected to a transducer for measuring the isometric force promoted by a vascular contraction. The arteries were exposed to increasing concentrations of polysorbate 80, amiodarone dissolved in water, amiodarone dissolved in polysorbate 80, and a commercial presentation of amiodarone (Cordarone). The experiments were conducted in the presence of the following enzymatic blockers: only indomethacin, Nω-nitro-L-arginine associated with indomethacin, and only Nω-nitro-L-arginine. ResultsPolysorbate 80 caused a small degree of nonendotheliumdependent relaxation. Cordarone, amiodarone dissolved in water, and amiodarone dissolved in polysorbate 80 caused endotheliumdependent relaxation, which was greater for amiodarone dissolved in polysorbate and for Cordarone. Only the association of indomethacin and Nω-nitro-L-arginine could eliminate the endothelium-dependent relaxation caused by amiodarone dissolved in polysorbate 80. ConclusionThe results obtained indicate that vasodilation promoted by amiodarone in canine coronary arteries is mainly caused by stimulation of the release of nitric oxide and cyclooxygenase-dependent relaxing endothelial factors.