International Journal of Pharmacology1811-77751812-5700Asian Network for Scientific Information10.3923/ijp.2006.341.347SaadWilson AbraoSiqueira GuardaIsmael Francisco MottaArruda. CamargoLuiz Antonio deSaadWilliam AbraoGuardaRenata SaadSantosTalmir A.F.B.SimoesSylvio 3200623The present study investigated the central role of angiotensin II and nitric oxide on arterial blood pressure (MAP) in rats. Losartan and PD123349 AT1 and AT 2 (selective no peptides antagonists angiotensin receptors), as well as FK 409 (a nitric oxide donor), NW-nitro-L-arginine methyl ester (L-NAME) a constituve nitric oxide synthase inhibitor endothelial (eNOSI) and 7-nitroindazol (7NI) a specific neuronal nitric oxide synthase inhibitor (nNOSI) were used. Holtzman strain, (Rattus norvergicus) weighting 200-250 g were anesthetized with zoletil 50 mg kg-1 (tiletamine chloridrate 125 mg and zolazepan chloridrate 125 mg) into quadriceps muscle and a stainless steel cannula was stereotaxically implanted into their Lateral Ventricle (LV). Controls were injected with a 0.5 μl volume of 0.15 M NaCl. Angiotensin II injected into LV increased MAP (19±3 vs. control 3±1 mm Hg), which is potentiated by prior injection of L-NAME in the same site 26±2 mm Hg. 7NI injected prior to ANG II into LV also potentiated the pressor effect of ANG II but with a higher intensity than L-NAME 32±3 mm Hg. FK 409 inhibited the pressor effect of ANG II (6±1 mm Hg). Losartan injected into LV before ANG II influences the pressor effect of ANG II (8±1 mm Hg). The PD 123319 decreased the pressor effects of ANG II (16±1 mm Hg). Losartan injected simultaneously with FK 409 blocked the pressor effect of ANG II (3±1 mm Hg). 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