The L-arginine-NO pathway has been implicated in the vasorelaxant effect of 17-β-oestradiol. Here we have addressed the involvement of two distinct activation steps of endothelial nitric oxide synthase (eNOS) in the 17-β-oestradiol-induced vasorelaxant effect on rat aortic rings. Rat aortic rings contracted with phenylephrine (PE) 1 μM relaxed in a concentration related fashion to 17-β-oestradiol water soluble cyclodextrin-encapsulated (E2) only when endothelium was present. The pure anti-oestrogen of E2 receptor ICI 182,780 (20 μM) significantly inhibited E2-induced vasorelaxation. Geldanamycin (10 μM), a specific inhibitor of heat shock protein 90 (hsp90) and Nω-nitro-L-arginine-methyl ester (L-NAME, 100 μM), a nitric oxide synthase inhibitor, significantly inhibited E2-induced vasorelaxation. Incubation of rat aortic rings up to 6 h with LY 294002 (25 μM), a specific inhibitor of PI(3)K akt/pkb pathway reduced E2-induced vasorelaxation. Incubation of rat isolated aorta with E2, induced prostacyclin (PGI2) release. PGI2 levels, measured as 6-keto PGF1α, were abolished by ibuprofen (10 μM), both L-NAME and GA did not influence basal or E2-stimulated PGI2 confirming the specificity of these two compounds on eNOS pathway. In conclusion, we demonstrate that E2 interaction with its receptor is followed by a vasorelaxant effect in rat aortic rings mediated by eNOS activation through both hsp90 and akt/pkb dependent mechanisms.

17-ß-oestradiol-induced vasorelaxation in vitro is mediated by eNOS through hsp90 and akt/pkb dependent mechanism

PINTO, Aldo;
2002

Abstract

The L-arginine-NO pathway has been implicated in the vasorelaxant effect of 17-β-oestradiol. Here we have addressed the involvement of two distinct activation steps of endothelial nitric oxide synthase (eNOS) in the 17-β-oestradiol-induced vasorelaxant effect on rat aortic rings. Rat aortic rings contracted with phenylephrine (PE) 1 μM relaxed in a concentration related fashion to 17-β-oestradiol water soluble cyclodextrin-encapsulated (E2) only when endothelium was present. The pure anti-oestrogen of E2 receptor ICI 182,780 (20 μM) significantly inhibited E2-induced vasorelaxation. Geldanamycin (10 μM), a specific inhibitor of heat shock protein 90 (hsp90) and Nω-nitro-L-arginine-methyl ester (L-NAME, 100 μM), a nitric oxide synthase inhibitor, significantly inhibited E2-induced vasorelaxation. Incubation of rat aortic rings up to 6 h with LY 294002 (25 μM), a specific inhibitor of PI(3)K akt/pkb pathway reduced E2-induced vasorelaxation. Incubation of rat isolated aorta with E2, induced prostacyclin (PGI2) release. PGI2 levels, measured as 6-keto PGF1α, were abolished by ibuprofen (10 μM), both L-NAME and GA did not influence basal or E2-stimulated PGI2 confirming the specificity of these two compounds on eNOS pathway. In conclusion, we demonstrate that E2 interaction with its receptor is followed by a vasorelaxant effect in rat aortic rings mediated by eNOS activation through both hsp90 and akt/pkb dependent mechanisms.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/1129012
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