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Discrepant Regulation of QT (QTc) Interval Duration by Calcium Channel Blockade and ACE Inhibition in Experimental Hypertension.
MedLine Citation:
PMID:  22626243     Owner:  NLM     Status:  Publisher    
Antihypertensive treatment may reduce prolonged QT duration in hypertension. Generally, the reductions of blood pressure and/or of cardiac mass are believed to be the responsible factors. However, drugs are not equivalent in QT modulation despite similar antihypertensive and antihypertrophic action. We investigated the effect of a calcium channel blocker, lacidipine and an angiotensine-converting enzyme inhibitor, enalapril on QT duration in rats. Normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were treated with lacidipine (at the dose of 1.5 mg/kg/d for WKY, and 3 mg/kg/d for SHR) or enalapril (5 mg/kg/d for WKY, and 10 mg/kg/d for SHR) during eight weeks. Tail-cuff systolic blood pressure (sBP), left ventricular weight (LVW), vascular function of isolated aorta and mesenteric artery, and duration of QT (and QTc) interval on Frank electrocardiograms were evaluated. As expected, untreated SHR showed elevated sBP, impaired vascular reactivity, increased LVW and prolonged QT when compared to WKY (P<0.05). Following treatment, both agents markedly improved vascular reactivity and reduced sBP in SHR (P<0.05). Additionally, enalapril reduced LVW in both hypertensive (by 17%; P<0.05) and normotensive rats (by 13%; P<0.05) and, consequently, corrected QT duration in SHR. Interestingly, also lacidipine reduced LVW in SHR (by 9%; P<0.05), but without influence on prolonged QT. Moreover, lacidipine had no effect on LVW in WKYs but prolonged their QT interval (by 10%; P<0.05). In conclusion, lacidipine did not reverse a progressive prolongation of QT in SHR, despite sBP lowering and LVW reduction. Thus, the lowering of blood pressure and/or reduction of LVW are not sufficient per se to normalize ventricular repolarization in hypertensive cardiac disease. More probably, modulation of QT prolongation by antihypertensive drugs is a function of their complex action on blood pressure, vascular function, cardiac mass and on reflex neurohumoral activation.
Jan Klimas; Vaclav Vaja; Miriam Vercinska; Jan Kyselovic; Peter Krenek
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-5-24
Journal Detail:
Title:  Basic & clinical pharmacology & toxicology     Volume:  -     ISSN:  1742-7843     ISO Abbreviation:  -     Publication Date:  2012 May 
Date Detail:
Created Date:  2012-5-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101208422     Medline TA:  Basic Clin Pharmacol Toxicol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
© 2012 The Authors Basic & Clinical Pharmacology & Toxicology © 2012 Nordic Pharmacological Society.
Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University, Bratislava, Slovak Republic.
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