首页 | 本学科首页   官方微博 | 高级检索  
检索        


Carotid body function in aged rats: responses to hypoxia,ischemia, dopamine,and adenosine
Authors:Teresa Castro Monteiro  Joana Rita Batuca  Ana Obeso  Constancio González  Emília Carreira Monteiro
Institution:1.Department of Pharmacology, CEDOC/Chronic Diseases Unit, Faculty of Medical Sciences,New University of Lisbon,Lisbon,Portugal;2.Department of Biochemistry, Molecular Biology and Physiology, Faculty of Medicine and IBGM,University of Valladolid,Valladolid,Spain;3.CSIC,CIBER de Enfermedades Respiratorias,Valladolid,Spain;4.Department of Pharmacology, Faculty of Medical Sciences,New University of Lisbon,Lisbon,Portugal
Abstract:The carotid body (CB) is the main arterial chemoreceptor with a low threshold to hypoxia. CB activity is augmented by A2-adenosine receptors stimulation and attenuated by D2-dopamine receptors. The effect of aging on ventilatory responses mediated by the CB to hypoxia, ischemia, and to adenosine and dopamine administration is almost unknown. This study aims to investigate the ventilatory response to ischemia and to adenosine, dopamine, and their antagonists in old rats, as well as the effect of hypoxia on adenosine 3′,5′-cyclic monophosphate (cAMP) accumulation in the aged CB. In vivo experiments were performed on young and aged rats anesthetized with pentobarbitone and breathing spontaneously. CB ischemia was induced by bilateral common carotid occlusions. cAMP content was measured in CB incubated with different oxygen concentrations. Hyperoxia caused a decrease in cAMP in the CB at all ages, but no differences were found between normoxia and hypoxia or between young and old animals. The endogenous dopaminergic inhibitory tonus is slightly reduced. However, both the ventilation decrease caused by exogenous dopamine and the increase mediated by A2A-adenosine receptors are not impaired in aged animals. The bradycardia induced by adenosine is attenuated in old rats. The CB’s peripheral control of ventilation is preserved during aging. Concerns have also arisen regarding the clinical usage of adenosine to revert supraventricular tachycardia and the use of dopamine in critical care situations involving elderly people.
Keywords:Aging  Peripheral chemoreceptors  Ventilation  Domperidone  cAMP  Adenosine A2A receptors
本文献已被 PubMed SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号