Effects of long-term angiotensin converting enzyme inhibition on cardiovascular variability in aging rats

Valdo José Dias Da Silva, Nicola Montano, Helio Cesar Salgado, Rubens Fazan

Research output: Contribution to journalArticle

Abstract

We studied the effects of chronic (4 weeks) angiotensin converting enzyme inhibition with captopril on arterial pressure (AP) and heart rate (HR) variability, as well as on cardiac baroreflex sensitivity (BRS), in aged (20 months) rats. Series of basal RR interval (RRi) and systolic AP (SAP) were studied by autoregressive spectral analysis with oscillations quantified in low (LF: 0.2-0.8 Hz) and high frequency (HF: 0.8-2.5 Hz). BRS was measured by linear regression between HR and MAP changes. Captopril did not affect the spectra of RRi or SAP in young rats. Aged rats presented a reduction in variance (time domain) and in LF and HF oscillations of RRi and SAP. Captopril induced, in aged rats, a decrease in absolute and normalized LF oscillations and in LF/HF ratio of RRi. Captopril also reduced the variance, without changing its LF or HF components of SAP. Reflex tachycardia was reduced in aged as compared to young rats (- 1.1 ± 0.2 versus - 3.4 ± 0.5 bpm/mm Hg) and captopril did not affect it. Reflex bradycardia was also reduced in aged rats (- 0.7 ± 0.5 versus - 2.0 ± 0.4 bpm/mm Hg), but captopril prevented this attenuation in aged rats (- 2.3 ± 0.3 versus - 0.7 ± 0.5 bpm/mm Hg). These data indicate that there is a reduction in HR and SAP variability during aging, suggesting impairment of cardiovascular autonomic control. Captopril was able to change the power of oscillatory components of RRi, suggesting a shift in cardiac sympatho/vagal balance toward parasympathetic predominance. In addition, blockage of ACE improved the reflex bradycardia, but not the reflex tachycardia in aged rats.

Original languageEnglish
Pages (from-to)49-55
Number of pages7
JournalAutonomic Neuroscience: Basic and Clinical
Volume124
Issue number1-2
DOIs
Publication statusPublished - Jan 30 2006

Keywords

  • ACE inhibitor
  • Aging
  • Baroreceptor
  • Heart rate variability
  • Rats

ASJC Scopus subject areas

  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Endocrine and Autonomic Systems

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