POLYCYCLIC AROMATIC HYDROCARBONS-INDUCED VASORELAXATION THROUGH ACTIVATION OF NITRIC-OXIDE SYNTHASE IN ENDOTHELIUM OF RAT AORTA

In the present study, the effect of polycyclic aromatic hydrocarbons ( PAHs) on isolated rat aorta was investigated. Acenaphthylene and napht halene dose-dependently relaxed the phenylephrine-induced contraction of rat aorta with 50% vasorelaxation at 40.8 +/- 19.83 and 118.75 +/- 9.83 mu M, respectively. The vasorelaxation effect was diminished in t he denuded (endothelium removed) aorta suggesting that the relaxation effect of PAHs was endothelium dependent. By comparing PAHs with diffe rent ring structures, we have found that acenaphthylene has the highes t potency to induce vasorelaxation. Pretreatment with the nitric oxide synthase inhibitor, L-N-G-nitroarginine methyl ester, and the guanyla te cyclase inhibitor, methylene blue, prevents the vasorelaxation indu ced by PAHs. These results indicate that the vasorelaxation effect of PAHs is mediated by activation of nitric oxide synthase of endothelium . (C) 1997 Elsevier Science Ireland Ltd.