Document Detail

Regional and species differences in vascular reactivity to extracellular potassium.
MedLine Citation:
PMID:  2782089     Owner:  NLM     Status:  MEDLINE    
In-vitro vasoreactivity to extracellular potassium (Ko+) was tested in isolated human pial and mesenteric arteries as well as basilar and mesenteric arteries from rabbits and rats. Contractions were induced by stepwise increases in [K+]o and were measured isometrically with a force-displacement transducer, in small-volume organ baths. Significant differences between species as well as between regions were found. The threshold of [K+]o for eliciting contraction in human cerebral arteries in hyperosmotic solutions was 10 mM, in rabbit cerebral arteries 17 mM and in rat cerebral arteries 27 mM. The threshold concentration for contraction in mesenteric arteries was significantly higher compared to cerebral arteries in humans and rabbits, but lower in rats: 20 mM in humans, 26 mM in rabbits and 25 mM in rats. In all species the contractile amplitudes were significantly higher in both cerebral and mesenteric arteries when [K+]o was increased under isotonic conditions in the buffer solution than when hyperosomolality was created. This difference increased with increasing hyperosmolality. In hyperosmotic solutions, the EC50 for [K+]o was lower in cerebral and mesenteric arteries from man than in vessels from rabbit and rat. When the solutions were isotonic, this pattern was seen only in mesenteric arteries. It is concluded that significant species and regional differences in vascular responses to [K+]o exist. Considering that [K+]o is increased in cerebral ischaemia, the observed significantly lower threshold for K+-induced contractions in human cerebral arteries may be of importance, especially in human cerebral ischaemic events.
T Ryman; L Brandt; K E Andersson; P Mellergård
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Acta physiologica Scandinavica     Volume:  136     ISSN:  0001-6772     ISO Abbreviation:  Acta Physiol. Scand.     Publication Date:  1989 Jun 
Date Detail:
Created Date:  1989-10-18     Completed Date:  1989-10-18     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0370362     Medline TA:  Acta Physiol Scand     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  151-9     Citation Subset:  IM    
Department of Clinical Pharmacology, Lund University Hospital, Sweden.
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MeSH Terms
Basilar Artery / drug effects
Cerebral Arteries / drug effects
Mesenteric Arteries / drug effects
Muscle Contraction / drug effects*
Muscle, Smooth, Vascular / drug effects*
Osmolar Concentration
Potassium / pharmacology*
Rats, Inbred Strains
Species Specificity
Vascular Resistance / drug effects*
Reg. No./Substance:

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