Document Detail

Aortic impedance and compliance in hypertensive rats.
MedLine Citation:
PMID:  2764136     Owner:  NLM     Status:  MEDLINE    
We compared aortic impedance and compliance in normotensive control and hypertensive Wistar rats. Hypertension was induced by unilateral nephrectomy plus steroid and salt water administration. After at least 8 wk of sustained hypertension (tail-cuff systolic pressures greater than 172 mmHg), open-chest ascending aortic micromanometric pressures and electromagnetic flows were measured. We used a frequency-modulated pacing method to enhance the energy content of the pressure and flow signals at specific low frequencies and their multiples. Impedance spectra were calculated using both Fourier series and spectral analysis methods. Compliance was calculated from the low-frequency impedance moduli, assuming a windkessel model for the arterial system. During pentobarbital sodium anesthesia under baseline conditions, the hypertensive rats had higher total resistance (219,000 vs. 126,000, higher characteristic impedance (7,334 vs. 5,377, larger first zero crossing of impedance phase angle (13.9 vs. 10 Hz), larger ratio of backward to forward pressure waves (0.67 vs. 0.48), and lower compliance (0.00498 vs. 0.00720 ml/mmHg) than controls. The differences between the groups were eliminated when the blood pressures of the hypertensive rats were normalized by vasodilation with nitroprusside or when the control rats were made hypertensive by vasoconstriction with phenylephrine. Thus the hemodynamic alterations appear to be secondary to the increased blood pressure. These base-line differences and the responses to vasoactive drugs are similar to findings in humans, suggesting that this rat model is a good hemodynamic model of human hypertension.
B D Zuckerman; F C Yin
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The American journal of physiology     Volume:  257     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1989 Aug 
Date Detail:
Created Date:  1989-09-14     Completed Date:  1989-09-14     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H553-62     Citation Subset:  IM    
Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205.
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MeSH Terms
Aorta / physiopathology*
Blood Pressure
Cardiac Output
Heart Rate
Hypertension, Renovascular / physiopathology*
Models, Cardiovascular
Muscle, Smooth, Vascular / physiopathology*
Rats, Inbred Strains
Reference Values
Stroke Volume
Vascular Resistance

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

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