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Journal of Renin-Angiotensin-Aldosterone System
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*Dietary Sodium
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*LOSARTAN POTASSIUM
*SODIUM
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Changing dietary sodium alters the chronic cardiovascular effects of losartan in rats

John P Collister

Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN 55108. USA, colli066@ umn.edu

David B Nahey

Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN 55108. USA

Introduction. We have previously demonstrated a profound hypotensive response to the angiotensin II type 1 (AT1)-receptor antagonist losartan in rats consuming a normal salt diet that is not seen in salt-loaded rats, presumably due to a suppression of the renin-angiotensin system (RAS) by high sodium levels.The purpose of the present study was to examine the cardiovascular effects of changing dietary sodium intake during chronic treatment with losartan.We hypothesised that during blockade of AT1-receptors by chronic losartan infusion, when renin levels would be elevated regardless of dietary sodium, changing diets from high to normal or normal to high salt would have no effect on mean arterial pressure (MAP).

Materials and methods. To test this hypothesis, groups of rats instrumented with radiotelemetry transducers for MAP monitoring and venous catheters for infusion were initially placed on either a 0.4% salt content diet, referred to as Losartan Normal diet — High salt diet (LosN-HI, n = 7), or a 4.0% salt content diet, referred to as U Losartan High salt diet — Normal diet (LosHI-N, n = 9). After a thee-day control period, infusion of losartan was begun in all rats (10 mg/kg/day in 7 ml/day isotonic saline i.v.).After 10 days, diets were switched between groups and data were collected for another 10 days, after which losartan infusion was terminated for a 10-day recovery period.

Results. At the start of losartan infusion MAP was observed to be similar between LosN-HI rats (101±2 mmHg) and LosHI-N rats (101±2 mmHg). By day seven of the first 10 day protocol, MAP in LosN-HI rats had fallen to 71±4 mmHg while decreasing to 90±2 mmHg in LosHI-N rats. Five days after switching diets, MAP in LosN-HI rats had risen back to 85±3 mmHg, while MAP in LosHI-N rats had fallen to 75±2 mmHg. Conclusions. These results do not support our hypothesis, suggesting that changing dietary sodium can alter the chronic hypotensive response to losartan regardless of the initial state of the RAS.

Key Words: blood pressure • dietary sodium • losartan • sodium and water balance

References

Journal of Renin-Angiotensin-Aldosterone System, Vol. 9, No. 1, 10-16 (2008)
DOI: 10.3317/jraas.2008.008
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This Article
Right arrow Abstract Freely available
Right arrow Free Full Text (Free PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Saved Citations
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Request Reprints
Right arrow Add to My Marked Citations
Citing Articles
Right arrow Citing Articles via Google Scholar
Right arrow Citing Articles via Scopus
Google Scholar
Right arrow Articles by Collister, J. P
Right arrow Articles by Nahey, D. B
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Collister, J. P
Right arrow Articles by Nahey, D. B
Right arrowPubmed/NCBI databases
*Compound via MeSH
*Substance via MeSH
Medline Plus Health Information
*Dietary Sodium
Hazardous Substances DB
*LOSARTAN POTASSIUM
*SODIUM
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati   Add to Twitter  
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