EFFECT OF NITRIC OXIDE IN THE VASORELAXANT ACTION OF ATRIAL NATRIURETIC PEPTIDE ON RABBIT AORTA BASAL TONE

ROMANO, LILIANA; JEREZ, SUSANA; COVIELLO, A; MARIA DE LOS ANGELES PERAL

CANADIAN JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY

Canada NRC Research Press

Lugar: Canada; Año: 2002 vol. 80 p. 1022 - 1029

0008-4212

Abstract: The role of nitric oxide (NO) on the vasorelaxant effect of atrial natriuretic peptide (ANP) in basal tone of angiotensin II (Ang II)-conditioned rabbit aortic rings was studied. ANP aortic relaxation and nitrite release were measured in the presence and absence of endothelium and a NO synthase inhibitor. Ang II 10-8 M triggered a contractile response  conditioning the vessel to a vasorelaxant effect of ANP. This effect was significantly enhanced by endothelium removal, L-NAME (10-4 M) and methylene blue (10-5 M). ANP decrease of basal tone in Ang II-sensitized aortic rings  was improved  when a higher concentration of Ang II was used (10-6 M). Basal and Ang II stimulated nitrite release was measured in stretched (S) and non-stretched (NS) aortic rings. Nitrite release was significantly increased in S rings (p<0.001). L-NAME (10-4 M)  partially inhibited nitrite release in both basal and Ang II-stimulated S aortic rings. In NS the NO inhibitor did not inhibit basal nitrite release but blunted the Ang II-stimulated nitrite level.   A significant negative correlation  between  nitrite release and ANP vasorelaxant effect on  basal tone was dependent on  Ang II-sensitizing dose. Present results demonstrate that ANP relaxant effect of aortic basal tone is related to NO levels which are regulated by S and Ang II-concentration dependent NO generation and quenching