Cardiovascular autonomic control in mice lacking angiotensin AT1a receptors

Cardiovascular autonomic control in mice lacking angiotensin AT1a receptors

Author Chen, Yan Fang Google Scholar
Joaquim, Luis F. Google Scholar
Farah, Vera M. Google Scholar
Wichi, Rogerio B. Autor UNIFESP Google Scholar
Razan Junior, Rubens Google Scholar
Salgado, Helio C. Google Scholar
Morris, Mariana Google Scholar
Institution Wright State Univ
Universidade Federal de São Paulo (UNIFESP)
Universidade de São Paulo (USP)
Abstract 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 mu g/g ip) and hexamethonium (30 mu g/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 mmHg2). 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.
Keywords heart rate
blood pressure
baroreflex
autonomic nervous system
spectral analysis
Language English
Date 2005-04-01
Published in American Journal of Physiology-regulatory Integrative and Comparative Physiology. Bethesda: Amer Physiological Soc, v. 288, n. 4, p. R1071-R1077, 2005.
ISSN 0363-6119 (Sherpa/Romeo, impact factor)
Publisher Amer Physiological Soc
Extent R1071-R1077
Origin http://dx.doi.org/10.1152/ajpregu.00231.2004
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000227827000037
URI http://repositorio.unifesp.br/handle/11600/28209

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