β-Blocker effects on respiratory sinus arrhythmia and baroreflex gain in normal subjects

Maria Vittoria Pitzalis, Filippo Mastropasqua, Francesco Massari, Andrea Passantino, Paolo Totaro, Cinzia Forleo, Paolo Rizzon

Research output: Contribution to journalArticlepeer-review

Abstract

Study objective: The results of studies on the effect of β-adrenergic blockade on respiratory sinus arrhythmia (RSA) are discordant. The aim of this study was to verify whether chronic β-adrenergic blockade is capable of increasing RSA, and therefore vagal outflow, and to analyze whether the mechanism of action is central or peripheral. Participants and design: Twenty normal subjects (28±2 years old) were randomized to receive a hydrophilic (nadolol) β-blocker, a lipophilic (metoprolol) β-blocker, and placebo. Measurements: After I week of therapy, a spectral analysis was made of the variability in heart rate and systolic BP during controlled breathing at 16 breaths/min. The high-frequency component was calculated for the RR interval (measure of RSA) and systolic pressure, and the squared coherence and phase functions were assessed between RR and systolic pressure fluctuations in the respiratory band; a negative phase means that RR changes follow systolic pressure changes. The gain in the relationship between the two signal fluctuations was also calculated. Results: Both β-blockers increased the mean (±SD)RR interval (placebo=808±21, nadolol=1,054±30, metoprolol=1,031±27 ms; p2; p=0.002), and the gain (placebo=13.6±1.5, nadolol=21.9±2.8, metoprolol= 24.5±3.6 ms/mm Hg; p

Original languageEnglish
Pages (from-to)185-191
Number of pages7
JournalChest
Volume114
Issue number1
Publication statusPublished - 1998

Keywords

  • Baroreflex sensitivity
  • Cross-spectral analysis
  • Humans
  • Hydrophilic β- blockers
  • Lipophilic β-blockers
  • Metoprolol
  • Nadolol
  • Respiratory sinus arrhythmia
  • Vagal activity

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

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