Document Detail

Relative importance of rostral ventrolateral medulla in sympathoinhibitory action of rilmenidine in conscious and anesthetized rabbits.
MedLine Citation:
PMID:  11243415     Owner:  NLM     Status:  MEDLINE    
The pressor region of the rostral ventrolateral medulla (RVLM) is a critical site in the sympathoinhibitory action of imidazoline receptor agonists as shown by studies in anesthetized animals. The aim of this study was to compare the importance of the RVLM in mediating the inhibitory action of rilmenidine on renal sympathetic nerve activity (RSNA) and arterial pressure in urethane-anesthetized rabbits (n = 11) and in conscious, chronically instrumented rabbits (n = 6). Bilateral microinjection of rilmenidine (4 nmol in 100 nl) into the RVLM caused a greater decrease in resting arterial pressure in anesthetized animals (-19 mm Hg) than in conscious animals (-8 mm Hg). By contrast, the decrease in resting RSNA evoked by rilmenidine was similar in conscious (-27%) and anesthetized (-36%) rabbits. Furthermore, rilmenidine microinjection into the RVLM was equally effective in inhibiting the RSNA baroreflex in both groups of animals. The upper plateau of the RSNA baroreflex decreased by 37% and 42%, and gain decreased by 41% and 44% after rilmenidine treatments in conscious and anesthetized rabbits, respectively. We conclude that the RVLM plays an equally important role in the inhibitory action of rilmenidine on RSNA in conscious and anesthetized rabbits either at rest or during baroreflex responses. A relatively moderate effect of rilmenidine on arterial pressure in conscious, chronically instrumented rabbits may relate to a lower level of sympathetic drive compared with anesthetized animals.
D N Mayorov; S L Burke; G A Head
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of cardiovascular pharmacology     Volume:  37     ISSN:  0160-2446     ISO Abbreviation:  J. Cardiovasc. Pharmacol.     Publication Date:  2001 Mar 
Date Detail:
Created Date:  2001-03-12     Completed Date:  2001-05-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7902492     Medline TA:  J Cardiovasc Pharmacol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  252-61     Citation Subset:  IM    
Baker Medical Research Institute, Prahran, Melbourne, Australia.
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MeSH Terms
Antihypertensive Agents / pharmacology*
Blood Pressure / drug effects
Kidney / innervation
Medulla Oblongata / drug effects*,  physiology
Oxazoles / pharmacology*
Pressoreceptors / drug effects,  physiology
Reflex / drug effects
Sympathetic Nervous System / drug effects*
Reg. No./Substance:
0/Antihypertensive Agents; 0/Oxazoles; 54187-04-1/rilmenidine

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