Caracterización de la liberación endotelial de óxido nítrico inducida por angiotensina II en aorta aislada de conejo.

S. JEREZ, M. PERAL DE BRUNO Y A. COVIELLO.

Tucuman, Tafi del Valle

Congreso; XV Jornadas de la Sociedad de Biología de Tucumán.; 1998

Sociedad de Biología de Tucumán.

Angiotensin II (Ang II) induces release of relaxing  (NO and prostaglandins) and contractile (endothelin) factors in endothelial cells. Objective: to characterize the release of NO by Ang II and the action of nonpeptide Ang II antagonists AT1 (losartan), AT2 (PD123319) and alfa2 adrnergic (yohimbine) receptors and the NO synthase inhibitor (L-NAME), in isolated rabbit aorta. Materials and methods: aortic rings were placed in Krebs solution at 37º C aereated with carbogen. In same rings different antagonists were added in equilibration period by 30 min, while Ang II at different doses was added in all rings by 20 min. Nitrite were determinated by Griess-method. Results: increased nitrite release by Ang II was dose dependent up to 10-6 M decreasing in higher concentration of Ang II.. L-NAME inhibited the effect of NO production. Losartan and PD 123319 increased Ang II-nitrite release only at 10-6 M, an effect that was blocked by yohimbine, which had effect by itself only at 5.10-6 M Ang II-nitrite release. Conclusions: Ang II at maximal doses would unmask nitrite release due to the stimulation of alfa2 endothelial receptors by norepinephrine liberated by Ang II in local endings nerves. At supramaximal doses inhibitory mechanisms dependent on AT1 and AT2 receptors would be triggered.