Fish Balistes capriscus skin extract-induced relaxation in mesenteric arterial bed of rat

The vasorelaxing activity of the aqueous extract of fish Balistes capriscus skin (AE Bc) on mesenteric arterial bed (MAB) of rats was studied. The bolus injections of AE Bc (bolus of 5.1, 10.2, 20.5, and 41.1 mg) significantly inhibited, in a concentration-dependent manner, the maximal contractile response induced by methoxamine (30 μM) in MAB. The vasodilatation action of AE Bc is not mediated through β-adrenoceptors or cyclo-oxigenase, since it was not affected by propranolol (20 μM) or diclofenac sodium (3 μM). The vasodilator response induced by subsequent addition of AE Bc Balistes capriscus in bolus was significantly reduced in water infusion for endothelium removal. Treatment with an inhibitor of NO synthase ( l-NAME, 10 μM) decreased AE Bc effect. The guanylate cyclase inhibitor methylene blue (MB, 100 μM) had no significant effect on AE Bc-induced vasodilatation. These results suggest that the vasorelaxing effect of AE Bc is mediated by endothelium-dependent (NO/EDRF) and endothelium-independent neurally induced vasorelaxation from nonadrenergic and noncholinergic nerves (NO).