Ovariectomy increases the participation of hyperpolarizing mechanisms in the relaxation of rat aorta
Entity
UAM. Departamento de FisiologíaPublisher
Public Library of ScienceDate
2013-09-13Citation
10.1371/journal.pone.0073474
Plos One 8.9 (2013): e73474
ISSN
1932-6203 (online)DOI
10.1371/journal.pone.0073474Funded by
This work was supported by grants (to MF) from the Fondo de Investigaciones Sanitarias (PI1100406)Subjects
Aorta; Rats; Ovariectomy; Vasodilation; Nitric Oxide; MedicinaRights
© 2013 Sagredo et al.Abstract
This study examines the downstream NO release pathway and the contribution of different vasodilator mediators in the acetylcholine-induced response in rat aorta 5-months after the loss of ovarian function. Aortic segments from ovariectomized and control female Sprague-Dawley rats were used to measure: the levels of superoxide anion, the superoxide dismutases (SODs) activity, the cGMP formation, the cGMP-dependent protein kinase (PKG) activity and the involvement of NO, cGMP, hydrogen peroxide and hyperpolarizing mechanisms in the ACh-induced relaxation. The results showed that ovariectomy did not alter ACh-induced relaxation; incubation with L-NAME, a NO synthase inhibitor, decreased the ACh-induced response to a lesser extent in aorta from ovariectomized than from control rats, while ODQ, a guanylate cyclase inhibitor, decreased that response to a similar extent; the blockade of hyperpolarizing mechanisms, by precontracting arteries with KCl, decreased the ACh-induced response to a greater extent in aortas from ovariectomized than those from control rats; catalase, that decomposes hydrogen peroxide, decreased the ACh-induced response only in aorta from ovariectomized rats. In addition, ovariectomy increased superoxide anion levels and SODs activity, decreased cGMP formation and increased PKG activity. Despite the increased superoxide anion and decreased cGMP in aorta from ovariectomized rats, ACh-induced relaxation is maintained by the existence of hyperpolarizing mechanisms in which hydrogen peroxide participates. The greater contribution of hydrogen peroxide in ACh-induced relaxation is due to increased SOD activity, in an attempt to compensate for increased superoxide anion formation. Increased PKG activity could represent a redundant mechanism to ensure vasodilator function in the aorta of ovariectomized rats
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Google Scholar:Sagredo Ana
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Campo Milán, Lara del
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Martorell, Aina
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Navarro Jiménez, Rocío
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Martín, María C.
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Blanco Rivero, Javier
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Ferrer Parra, Mercedes
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