Document Detail


Baroreceptor-independent renal nerve inhibition by intracerebroventricular angiotensin II in conscious sheep.
MedLine Citation:
PMID:  9277539     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effect of central administration of angiotensin II (ANG II) on efferent renal sympathetic nerve activity (RSNA) was studied in conscious sheep. ANG II (1 nmol/h), infused for 30 min into the lateral cerebral ventricles in five sheep, did not alter mean arterial pressure (MAP) but reduced RSNA to 38 +/- 5% of control. Intracerebroventricular infusion of higher doses of ANG II (3 and 10 nmol/h), which increased MAP by 12 +/- 2 and 14 +/- 3 mmHg, respectively, reduced RSNA to 9 +/- 5 and 11 +/- 7% of control. MAP and RSNA gradually returned to control over a period of 2 h after the infusions. Intracerebroventricular losartan (1 mg/h for 1 h before, and then during, angiotensin infusion) blocked all the effects of angiotensin (3 nmol/h). Baroreflex relationships constructed from the beat-to-beat relationship of RSNA to diastolic pressure showed a significant leftward shift during intracerebroventricular ANG II compared with the control relationship. The beat-to-beat relationship between central venous pressure and RSNA was abolished during intracerebroventricular infusion of ANG II. These findings demonstrate that intracerebroventricular ANG II has a direct central inhibitory action on RSNA that is independent of both arterial and low-pressure baroreceptors. This effect of angiotensin is mediated by central angiotensin AT-1 receptors.
Authors:
C N May; R M McAllen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  273     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1997 Aug 
Date Detail:
Created Date:  1997-09-25     Completed Date:  1997-09-25     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  R560-7     Citation Subset:  IM    
Affiliation:
Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Australia.
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MeSH Terms
Descriptor/Qualifier:
Angiotensin II / pharmacology*
Animals
Antihypertensive Agents / pharmacology
Biphenyl Compounds / pharmacology
Blood Pressure / drug effects,  physiology
Central Venous Pressure / drug effects
Female
Imidazoles / pharmacology
Injections, Intraventricular
Kidney / innervation*
Losartan
Neural Inhibition*
Phenylephrine / pharmacology
Pressoreceptors / physiology*
Sheep
Sympathetic Nervous System / drug effects*,  physiology*
Tetrazoles / pharmacology
Chemical
Reg. No./Substance:
0/Antihypertensive Agents; 0/Biphenyl Compounds; 0/Imidazoles; 0/Tetrazoles; 11128-99-7/Angiotensin II; 114798-26-4/Losartan; 59-42-7/Phenylephrine

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