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Ghrelin modulates baroreflex-regulation of sympathetic vasomotor tone in healthy humans.
MedLine Citation:
PMID:  22492814     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Ghrelin, a neuropeptide originally known for its growth hormone-releasing and orexigenic properties, exerts important pleiotropic effects on the cardiovascular system. Growing evidence suggests that these effects are mediated by the sympathetic nervous system. The present study aimed at elucidating the acute effect of ghrelin on sympathetic outflow to the muscle vascular bed (MSNA) and on baroreflex-mediated arterial blood pressure (BP) regulation in healthy humans. In a randomized double-blind cross-over design 12 lean young men were treated with a single dose of either ghrelin 2 µg/kg i.v. or placebo (isotonic saline). MSNA, heart rate (HR) and BP were recorded continuously from 30 minutes before until 90 minutes after substance administration. Sensitivity of arterial baroreflex was repeatedly tested by injection of vasoactive substances based on the modified Oxford protocol. Early, i.e. during the initial 30 minutes after ghrelin injection BP significantly decreased together with a transient increase of MSNA and HR. In the course of the experiment (>30 minutes) BP approached placebo level while MSNA and HR were significantly lower compared to placebo. The sensitivity of vascular arterial baroreflex significantly increased at 30-60 minutes after ghrelin i.v. compared to placebo, while HR response to vasoactive drugs was unaltered. Our findings suggest two distinct phases of ghrelin action: In the immediate phase BP is decreased presumably due to its vasodilating effects which trigger baroreflex-mediated counter-regulation with increases of HR and MSNA. In the delayed phase central nervous sympathetic activity is suppressed, accompanied by an increase of baroreflex-sensitivity.
Authors:
Alexander Friedrich Krapalis; Jacqueline Reiter; Felix Machleidt; K Alexander Iwen; Christoph Dodt; Hendrik Lehnert; Friedhelm Sayk
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-4-4
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  -     ISSN:  1522-1490     ISO Abbreviation:  -     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-4-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1University Hospital of Schleswig-Holstein, Campus Luebeck.
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