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The phytoestrogen genistein enhances endothelium-independent relaxation in the porcine coronary artery

2003; Elsevier BV; Volume: 481; Issue: 2-3 Linguagem: Inglês

10.1016/j.ejphar.2003.09.028

1879-0712

Mary Y. K. Lee, Ricky Y.K. Man,

Estrogen and related hormone effects

Genistein, a phytoestrogen, possesses cardioprotective effects. Responses to genistein (0.1–100 μM) were assessed in 9,11-dideoxy-9α, 11α-methanoepoxy prostaglandin F2α (U46619)-contracted porcine coronary arterial rings, with significant relaxations at high concentrations. At concentrations with little relaxation, genistein (0.3–3 μM) did not affect relaxation produced by bradykinin and the calcium ionophore, A23187. In contrast, sodium nitroprusside- and cromakalim-induced relaxations were enhanced by genistein (3 μM). Nω-nitro-l-arginine methyl ester (l-NAME) (300 μM) or Triton X-100 (0.5%) did not affect the enhancement of relaxation by genistein. The tyrosine kinase inhibitor, tyrphostin 23 (30 μM), had no effect on sodium nitroprusside-elicited relaxation. In summary, genistein relaxed porcine coronary artery at relatively high concentrations. At a physiologically relevant concentration (3 μM), it is devoid of significant vascular effect, but enhanced endothelium-independent relaxations. This effect of genistein does not involve the nitric oxide synthase (NOS) pathway and the endothelium, and is mediated through a mechanism different from tyrosine kinase inhibition.