Document Detail

Identification of a renin threshold and its relationship to salt intake in a patient with pure autonomic failure.
MedLine Citation:
PMID:  9369257     Owner:  NLM     Status:  MEDLINE    
Animal studies have demonstrated a threshold below which renin release increases proportionally to a decrease in renal perfusion pressure. Demonstration of a similar mechanism in humans, however, has proved difficult, as any attempt to lower blood pressure below the putative renin threshold results in renin release mediated by reflex activation of the sympathetic nervous system. In this study, we report on our observations in a 71-year-old woman who presented with a 20-year history of faintness and syncope and was diagnosed as having pure autonomic failure. Graded head-up tilting resulted in a stepwise reduction in mean arterial blood pressure to a minimum of 54 mm Hg, with no signs of increased sympathetic activity. A fall in blood pressure below 80 mm Hg resulted in a distinct rise in plasma renin activity, and a similar threshold pressure was observed under both a 50- and a 100-mmol/d sodium chloride diet. Below the threshold, response to changes in perfusion pressure was proportionally greater under the 50-mmol/d diet than under a 100- or 200-mmol/d diet. These observations demonstrate that a pressure threshold for renin release at 10 to 15 mm Hg below ambient blood pressure, as described previously in animal studies, is also present in humans. The significance of this pressure-dependent mechanism of renin release for the long-term regulation of blood pressure and water and mineral balance in humans remains to be determined.
H Hohenbleicher; F Klosterman; U Schorr; S Seyfert; P B Persson; A M Sharma
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Publication Detail:
Type:  Case Reports; Journal Article    
Journal Detail:
Title:  Hypertension     Volume:  30     ISSN:  0194-911X     ISO Abbreviation:  Hypertension     Publication Date:  1997 Nov 
Date Detail:
Created Date:  1997-12-10     Completed Date:  1997-12-10     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  7906255     Medline TA:  Hypertension     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1068-71     Citation Subset:  IM; S    
Department of Internal Medicine, Universitätsklinikum Benjamin Franklin, Free University of Berlin, Germany.
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MeSH Terms
Autonomic Nervous System Diseases / blood*,  physiopathology
Blood Pressure / physiology
Diet, Sodium-Restricted*
Differential Threshold
Head-Down Tilt / physiology
Renin / blood*
Reg. No./Substance:

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