Document Detail

Effect of ouabain in pressurized middle cerebral arteries from normotensive and hypertensive rats.
MedLine Citation:
PMID:  10327389     Owner:  NLM     Status:  MEDLINE    
The aim of the present study was to assess the ability of ouabain to induce vasomotor responses and interfere with the myogenic tone in isolated segments of middle cerebral arteries from male Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) subjected to different pressures and no-flow conditions using a pressure myograph. At 60 mmHg, ouabain (1 nM-1 mM) caused relaxations at concentrations of 10 microM and up in segments from WKY while 1 nM ouabain produced a relaxation that was unaltered by the remaining concentrations in SHR segments. The relaxations were higher in SHR than in WKY arteries. Endothelium removal practically abolished the relaxation in arteries from both strains, whereas 10 microM L-NAME (an inhibitor of nitric oxide synthase) had no effect. When arteries were pressurized from 20-120 mmHg, myogenic activity developed in 3 out of 10 WKY arteries while SHR arteries did not show myogenic tone. Endothelium removal did not alter the effects of pressure increase in both strains, and incubation of segments in a Ca(2+)-free medium to abolish myogenic tone, shifted the pressure-response curve of WKY segments to the left; pressure-response curves from SHR were not modified. Although ouabain (0.1 mM) did not alter the pressure-response curve from WKY segments, curves obtained from SHR were shifted to the left. These results suggest that: 1) ouabain produces vasodilation in pressurized middle cerebral arteries of WKY and SHR which is positively modulated by an endothelial factor distinct from nitric oxide; and 2) only WKY arteries develop myogenic activity while the diameter of SHR arteries is passively enhanced with increases in intraluminal pressure. This passive increase is facilitated by ouabain. Therefore, hypertension modifies the mechanical properties of cerebral arteries resulting in a loss in the capacity for autoregulation.
R González; A M Manso; J Marín
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Methods and findings in experimental and clinical pharmacology     Volume:  21     ISSN:  0379-0355     ISO Abbreviation:  Methods Find Exp Clin Pharmacol     Publication Date:  1999 Mar 
Date Detail:
Created Date:  1999-07-16     Completed Date:  1999-07-16     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7909595     Medline TA:  Methods Find Exp Clin Pharmacol     Country:  SPAIN    
Other Details:
Languages:  eng     Pagination:  89-97     Citation Subset:  IM    
Department of Pharmacology and Therapeutics, Faculty of Medicine, Universidad Autónoma, Madrid, Spain.
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MeSH Terms
Blood Pressure / drug effects,  physiology
Cerebral Arteries / drug effects*,  physiology
Endothelium, Vascular / drug effects*
Enzyme Inhibitors / pharmacology*
NG-Nitroarginine Methyl Ester / pharmacology
Ouabain / pharmacology*
Rats, Inbred SHR
Rats, Inbred WKY
Vasodilation / drug effects*
Reg. No./Substance:
0/Enzyme Inhibitors; 50903-99-6/NG-Nitroarginine Methyl Ester; 630-60-4/Ouabain

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