Frequency-dependent baroreflex modulation of blood pressure and heart rate variability in conscious mice

Rubens Fazan, Mauro De Oliveira, Valdo José Dias Da Silva, Luis Fernando Joaquim, Nicola Montano, Alberto Porta, Mark W. Chapleau, Helio C. Salgado

Research output: Contribution to journalArticlepeer-review

Abstract

The goal of this study was to determine the baroreflex influence on systolic arterial pressure (SAP) and pulse interval (PI) variability in conscious mice. SAP and PI were measured in C57B1/6J mice subjected to sinoaortic deafferentation (SAD, n = 21) or sham surgery (n = 20). Average SAP and PI did not differ in SAD or control mice. In contrast, SAP variance was enhanced (21 ± 4 vs. 9.5 ± 1 mmHg2) and PI variance reduced (8.8 ± 2 vs. 26 ± 6 ms2) in SAD vs. control mice. High-frequency (HF: 1-5 Hz) SAP variability quantified by spectral analysis was greater in SAD (8.5 ± 2.0 mmHg2) compared with control (2.5 ± 0.2 mmHg2) mice, whereas low-frequency (LF: 0.1-1 Hz) SAP variability did not differ between the groups. Conversely, LF PI variability was markedly reduced in SAD mice (0.5 ± 0.1 vs. 10.8 ± 3.4 ms2). LF oscillations in SAP and PI were coherent in control mice (coherence = 0.68 ± 0.05), with changes in SAP leading changes in PI (phase = -1.41 ± 0.06 radians), but were not coherent in SAD mice (coherence = 0.08 ± 0.03). Blockade of parasympathetic drive with atropine decreased average PI, PI variance, and LF and HF PI variability in control (n = 10) but had no effect in SAD (n = 6) mice. In control mice, blockade of sympathetic cardiac receptors with propranolol increased average PI and decreased PI variance and LF PI variability (n = 6). In SAD mice, propranolol increased average PI (n = 6). In conclusion, baroreflex modulation of PI contributes to LF, but not HF PI variability, and is mediated by both sympathetic and parasympathetic drives in conscious mice.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume289
Issue number5 58-5
DOIs
Publication statusPublished - Nov 2005

Keywords

  • Blood pressure lability
  • Heart rate variability
  • Mice
  • Sinoaortic denervation
  • Spectral analysis

ASJC Scopus subject areas

  • Physiology

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