Document Detail


Hypertension increases middle cerebral artery resting tone in spontaneously hypertensive rats: role of tonic vasoactive factor availability.
MedLine Citation:
PMID:  18092943     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The present study explores the contribution of alterations in resting tone to cerebral artery narrowing in SHRs (spontaneously hypertensive rats) and the role of hypertension development. Young pre-hypertensive and adult fully hypertensive SHRs and age-matched Wistar-Kyoto rat controls were used. The contribution of basal vasoactive factors to resting tone was studied in middle cerebral arteries with pressure myography. Basal NO and O(2)(-) (superoxide anion) availability were determined with fluorescent indicators using confocal microscopy and lucigenin-enhanced chemiluminescence. Basal O(2)(-) was also assessed in mesenteric resistance arteries. Middle cerebral arteries from adult rats, but not young pre-hypertensive rats, had augmented myogenic responses and resting tone and decreased relaxation to sodium nitroprusside compared with their normotensive counterparts. Cerebral arteries from adult SHRs also had an increase in tonic NO associated with a decrease in basal O(2)(-) availability. Basal O(2)(-) was instead increased in mesenteric arteries from SHRs. The present results indicate that large cerebral arteries from SHRs have an increase in their resting tone as a consequence of sustained hypertension and that this is related to a decrease in NO responsiveness. We suggest that this increase in resting tone and myogenic responses could act as a protective mechanism against the development of stroke in SHRs. The present study also demonstrates some unusual findings regarding the current understanding of the NO/O(2)(-) balance in hypertension with important differences between vascular beds and draws attention to the complexity of this balance in cardiovascular health and disease.
Authors:
José M González; Beatriz Somoza; M Victoria Conde; Maria S Fernández-Alfonso; M Carmen González; Silvia M Arribas
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Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Clinical science (London, England : 1979)     Volume:  114     ISSN:  1470-8736     ISO Abbreviation:  Clin. Sci.     Publication Date:  2008 May 
Date Detail:
Created Date:  2008-04-10     Completed Date:  2008-05-08     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7905731     Medline TA:  Clin Sci (Lond)     Country:  England    
Other Details:
Languages:  eng     Pagination:  651-9     Citation Subset:  IM    
Affiliation:
Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, 28029 Madrid, Spain.
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MeSH Terms
Descriptor/Qualifier:
Animals
Biological Markers / analysis
Chemiluminescent Measurements
Hypertension / physiopathology*
Male
Microscopy, Confocal
Middle Cerebral Artery / metabolism,  physiopathology*
Muscle Tonus / drug effects
Muscle, Smooth, Vascular / metabolism,  physiopathology*
Nitric Oxide / analysis
Nitric Oxide Synthase / antagonists & inhibitors
Nitroprusside / pharmacology
Rats
Rats, Inbred SHR
Rats, Inbred WKY
Superoxides / analysis
Chemical
Reg. No./Substance:
0/Biological Markers; 10102-43-9/Nitric Oxide; 11062-77-4/Superoxides; 15078-28-1/Nitroprusside; EC 1.14.13.39/Nitric Oxide Synthase

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