Document Detail


Atrial natriuretic factor and brain natriuretic peptide gene expression in the spontaneous hypertensive rat during postnatal development.
MedLine Citation:
PMID:  9715795     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The increase in natriuretic peptides (NP), atrial natriuretic factor (ANF), and brain natriuretic peptide (BNP) production and release by cardiocytes that occurs in hypertension has been considered to be a compensatory mechanism against ventricular overload. Studies on NP production in the spontaneously hypertensive rat (SHR), an experimental model of human hypertension, have produced controversial results and were carried out when hypertension was already established (> 17 weeks). At this time, age-related physiologic and molecular changes in cardiac muscle are difficult to separate from those related to hypertension, ie, increased ANF production and plasma levels. In addition, most of the studies used male rats because the rate of increase in arterial blood pressure--as well as the level to which it rises--is greater in males than in females. Studies of a similar nature using female SHR are not available. The aim of this work was to determine 1) whether ANF and BNP production and secretion increase with the development of hypertension in genetically hypertensive rats; 2) whether a sexual dimorphism in ANF and BNP production and secretion is present in the genetically hypertensive rat during the development of hypertension; and 3) whether the demand for ANF and BNP is the same from each chamber of the heart under these experimental conditions. Age-matched male and female SHR, Wistar-Kyoto (WKY), and Sprague Dawley (SD) rats at 2, 4, and 8 weeks of age were used. The normotensive SD were included to provide a wider basis for baseline findings, as WKY rats are not always a suitable control for SHR due to genetic variations. Natriuretic peptide plasma levels and tissue content were measured by radioimmunoassay. ANF, BNP, as well as alpha- and beta-myosin heavy chain (MHC) mRNA were estimated by Northern blot analysis. Blood pressure (BP) of more than 150 mm Hg was found only in 8-week-old male SHR. Plasma immunoreactive (ir)ANF and irBNP increased significantly at puberty (8 weeks) in both male and female SHR. The earliest molecular change encountered during the development of hypertension was a significant increase in BNP mRNA in the right and left atria from both male and female 8-week-old SHR. In the ventricles from both male and female SHR, there was no increase in the ratio of left ventricular wet weight/body weight, no increase in ventricular ANF mRNA transcripts, and no myosin heavy chain isoform switch (a protein marker of hypertrophy). irBNP ventricular concentration, however, increased significantly in both male and female SHR, but only in female SHR was there a concomitant increase in BNP mRNA. These results suggest that 1) ANF and BNP production are not coordinated in all cardiac compartments during the development of hypertension; 2) upregulation of BNP in the atria from male and female SHR is the earliest event detected at 8 weeks; 3) the prehypertensive stage, in the genetically hypertensive female rats, is associated with an increase in ventricular irBNP concentration and BNP mRNA; 4) there is a dissociation between BP and plasma levels of NP; and 5) as well, there is a dissociation between NP gene expression and MHC isoform switch. The regulation of NP is not coordinated in either gender during the development of hypertension. The activation of the BNP gene in female SHR suggests that BNP might play an important role at the onset of hypertension.
Authors:
M L Kuroski de Bold
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of hypertension     Volume:  11     ISSN:  0895-7061     ISO Abbreviation:  Am. J. Hypertens.     Publication Date:  1998 Aug 
Date Detail:
Created Date:  1998-10-22     Completed Date:  1998-10-22     Revised Date:  2009-02-24    
Medline Journal Info:
Nlm Unique ID:  8803676     Medline TA:  Am J Hypertens     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1006-18     Citation Subset:  IM    
Affiliation:
Department of Pathology, University of Ottawa Heart Institute, Ottawa Civic Hospital, ON, Canada. mercedes@uottawa.ca
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MeSH Terms
Descriptor/Qualifier:
Age Factors
Animals
Atrial Natriuretic Factor / biosynthesis,  genetics*
Blood Pressure
Body Weight
Female
Gene Expression
Heart Ventricles / metabolism
Hypertension / metabolism*
Male
Natriuretic Peptide, Brain
Nerve Tissue Proteins / genetics*
Rats
Rats, Inbred SHR
Rats, Inbred WKY
Rats, Sprague-Dawley
Sex Factors
Chemical
Reg. No./Substance:
0/Nerve Tissue Proteins; 0/atrial natriuretic peptide, rat; 114471-18-0/Natriuretic Peptide, Brain; 85637-73-6/Atrial Natriuretic Factor

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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