Document Detail

Remission of high blood pressure reverses arterial potassium channel alterations.
MedLine Citation:
PMID:  8206632     Owner:  NLM     Status:  MEDLINE    
Rat arterial muscle cells show an elevated Ca(2+)-dependent K+ efflux during the established phase of hypertension. This association of enhanced K+ efflux with high arterial pressure implies that changes of in vivo blood pressure can alter the level of K+ channel current in arterial membranes. We directly tested this hypothesis by comparing K+ current density between patch-clamped aortic muscle membranes of normotensive Wistar-Kyoto (WKY) rats, spontaneously hypertensive rats (SHR), and SHR treated with the angiotensin-converting enzyme inhibitor ramipril (3.5 mg/kg per day PO) to normalize blood pressure. Peak macroscopic K+ current was measured during progressive depolarizing steps (10 mV) from -60 and +60 mV in cells dialyzed with pipette solution containing 10(-6) mol/L calcium to amplify Ca(2+)-dependent K+ current. With the use of this approach, maximum K+ current density in aortic muscle membranes of untreated SHR was 2.6-fold higher than in untreated WKY rats (SHR, 31 +/- 3 pA/pF; WKY, 12 +/- 1 pA/pF) and was predominantly blocked by 2 mmol/L tetraethylammonium. K+ current density in SHR aortic membranes was unchanged after 1 week of ramipril therapy, but it was reduced 42% (to 18 +/- 1 pA/pF) after 2 weeks of treatment. Parallel tension-recording studies showed that untreated SHR aortic segments but not aortic segments from WKY rats or ramipril-treated SHR constricted strongly after block of Ca(2+)-dependent K+ channels by tetraethylammonium. Our findings imply that Ca(2+)-dependent K+ current density in arterial muscle membranes shows a positive correlation with chronic arterial blood pressure levels.(ABSTRACT TRUNCATED AT 250 WORDS)
N J Rusch; A M Runnells
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Hypertension     Volume:  23     ISSN:  0194-911X     ISO Abbreviation:  Hypertension     Publication Date:  1994 Jun 
Date Detail:
Created Date:  1994-07-11     Completed Date:  1994-07-11     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7906255     Medline TA:  Hypertension     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  941-5     Citation Subset:  IM    
Department of Physiology, Medical College of Wisconsin, Milwaukee 53226.
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MeSH Terms
Aorta / metabolism*
Blood Pressure / drug effects
Hypertension / drug therapy,  metabolism*,  physiopathology*
Muscle, Smooth, Vascular / metabolism
Potassium Channel Blockers
Potassium Channels / metabolism*,  physiology
Ramipril / therapeutic use
Rats, Inbred SHR
Rats, Inbred WKY
Tetraethylammonium Compounds / pharmacology
Grant Support
Reg. No./Substance:
0/Potassium Channel Blockers; 0/Potassium Channels; 0/Tetraethylammonium Compounds; 66-40-0/Tetraethylammonium; 87333-19-5/Ramipril

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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