Document Detail

Cardiovascular autonomic control in mice lacking angiotensin AT1a receptors.
MedLine Citation:
PMID:  15576667     Owner:  NLM     Status:  MEDLINE    
Studies examined the role of angiotensin (ANG) AT1a receptors in cardiovascular autonomic control by measuring arterial pressure (AP) and heart rate (HR) variability and the effect of autonomic blockade in mice lacking AT1a receptors (AT1a -/-). Using radiotelemetry in conscious AT1a +/+ and AT1a -/- mice, we determined 1) AP and pulse interval (PI) variability in time and frequency (spectral analysis) domains, 2) AP response to alpha(1)-adrenergic and ganglionic blockade, and 3) intrinsic HR after ganglionic blockade. Pulsatile AP was recorded (5 kHz) for measurement of AP and PI and respective variability. Steady-state AP responses to prazosin (1 microg/g ip) and hexamethonium (30 microg/g ip) were also measured. AP was lower in AT1a -/- vs. AT1a +/+, whereas HR was not changed. Prazosin and hexamethonium produced greater decreases in mean AP in AT1a -/- than in AT1a +/+. The blood pressure difference was marked after ganglionic blockade (change in mean AP of -44 +/- 10 vs. -18 +/- 2 mmHg, AT1a -/- vs. AT1a +/+ mice). Intrinsic HR was also lower in AT1a -/- mice (431 +/- 32 vs. 524 +/- 22 beats/min, AT1a -/- vs. AT1a +/+). Beat-by-beat series of systolic AP and PI were submitted to autoregressive spectral estimation with variability quantified in low-frequency (LF: 0.1-1 Hz) and high-frequency (HF: 1-5 Hz) ranges. AT1a -/- mice showed a reduction in systolic AP LF variability (4.3 +/- 0.8 vs. 9.8 +/- 1.3 mmHg(2)), with no change in HF (2.7 +/- 0.3 vs. 3.3 +/- 0.6 mmHg(2)). There was a reduction in PI variability of AT1a -/- in both LF (18.7 +/- 3.7 vs. 32.1 +/- 4.2 ms(2)) and HF (17.7 +/- 1.9 vs. 40.3 +/- 7.3 ms(2)) ranges. The association of lower AP and PI variability in AT1a -/- mice with enhanced AP response to alpha(1)-adrenergic and ganglionic blockade suggests that removal of the ANG AT1a receptor produces autonomic imbalance. This is seen as enhanced sympathetic drive to compensate for the lack of ANG signaling.
Yanfang Chen; Luis F Joaquim; Vera M Farah; Rogério B Wichi; Rubens Fazan; Helio C Salgado; Mariana Morris
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.     Date:  2004-12-02
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  288     ISSN:  0363-6119     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2005 Apr 
Date Detail:
Created Date:  2005-03-28     Completed Date:  2005-04-15     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R1071-7     Citation Subset:  IM    
Department of Pharmacology and Toxicology, Wright State University School of Medicine, 3640 Colonel Glenn Hwy., Dayton, OH 45435, USA.
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MeSH Terms
Adrenergic alpha-Antagonists / pharmacology
Antihypertensive Agents / pharmacology
Autonomic Nervous System / physiology*
Baroreflex / drug effects,  physiology
Blood Pressure / physiology
Ganglionic Blockers / pharmacology
Heart Rate / physiology
Hemodynamics / physiology*
Hexamethonium / pharmacology
Mice, Knockout
Prazosin / pharmacology
Receptor, Angiotensin, Type 1 / genetics,  metabolism*
Receptors, Adrenergic, alpha-1 / drug effects,  physiology
Grant Support
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 0/Antihypertensive Agents; 0/Ganglionic Blockers; 0/Receptor, Angiotensin, Type 1; 0/Receptors, Adrenergic, alpha-1; 19216-56-9/Prazosin; 60-26-4/Hexamethonium

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