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Aging effects on carotid body and vascular responses from rats exposed to chronic intermittent hypoxia

AuthorsOlea, Elena ; Docio, Inmaculada; Gallego-Martin, Teresa ; Obeso, Ana ; Agapito, Teresa ; Gómez-Niño, A.; Rocher, Asunción
KeywordsCarotid body
Intermittent hypoxia
Issue Date2016
CitationXXXVIII Congreso SECF (2016)
AbstractChronic Intermittent Hypoxia (CIH) is considered one of the main causes of cardiovascular and metabolic alterations observed in the obstructive sleep apnea syndrome. Repetitive episodes of hypoxia/re-oxygenation produce oxidative stress and inflammation that could predispose to cumulative injury and acceleration of the aging process. Previous observations show that deleterious effects of CIH seem to be less pronounced in aged animals. It has also been reported that CIH produces sympathetic hyperactivity, endothelial dysfunction and systemic hypertension. Carotid body (CB) sensitization by recurrent hypoxic stimulation has been proposed as the origin of these alterations. The aim of this study is to compare vascular and CB responses and hypertensive changes in young and aged animals exposed to CIH, relating age and CIH induced effects. Four groups of male Wistar rats were used: young (3 months; n=32) and aged (18 months; n=32) in normoxia (C 3/18 months; n=16) and exposed to (21% O2-80 s/5% O2-40s 8h/day; 14 days) CIH (3/18 months; n=16). Ventilatory responsiveness to hypoxic and hypercapnic test was measured by whole body plethysmography. Aged rats ventilated less than younger under any conditions. On animals anaesthetized with ketamine (100 mg/Kg) and diazepam (5 mg/Kg; ip.), blood pO2, pCO2 and SatO2 were analyzed by gasometry at different inspired air O2 percentages (5-21%). In old control and CIH rats, SatO2 at PO2 ≤50 mmHg was lower than in young control rats. Mean arterial blood pressure (MABP) and pulse pressure were higher in aged than young control rats but got similar values after CIH. Vascular contractile responses were studied by wire myography. Using external carotid arteries, wall tension generated in response to phenylephrine (0.01 to 3μM) was higher in aged and CIH than young control rat arteries. Carbachol (10 μM) dependent relaxations were greater in young control than in aged and CIH rat arteries. Larger MABP and vascular properties alterations in aged animals could explain the lack of MABP increase observed in old rats after CIH. Conversely, CIH enhanced the CB secretory response to hypoxia (5% O2) in young and aged rats (250 vs. 300%), correlating with Cai 2+ increases in freshly dissociated chemoreceptor cells. Mechanisms underlying the enhanced CB reactivity to hypoxia induced by CIH could be due to a pro-oxidative status, as observed in other tissues.
DescriptionResumen del póster presentado al XXXVIII Congreso de la Sociedad Española de Ciencias Fisiológicas (SECF), celebrado en Zaragoza del 13 al 16 de septiembre de 2016.
Appears in Collections:(IBGM) Comunicaciones congresos
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