Heart rate and arterial pressure variability and baroreflex sensitivity in ovariectomized spontaneously hypertensive rats

Valdo José Dias da Silva, Rodrigo Miranda, Luciano Oliveira, Carlos Henrique F Rodrigues Alves, Glaucia Helana Fortes Van Gils, Alberto Porta, Nicola Montano

Research output: Contribution to journalArticle

Abstract

Aims: The present study evaluated the effects of ovariectomy on heart rate and arterial pressure variability and cardiac baroreflex sensitivity (BRS) in female spontaneously hypertensive (SHR) and Wistar-Kyoto rats (WKY). Main methods: Sham-surgery animals were used as control. Sixteen weeks after ovariectomy or sham-surgery, animals were recorded. Time series of pulse interval (PI) and systolic AP (SAP) were analyzed by means of autoregressive spectral analysis, which quantifies the power of very low (VLF = 0.01-0.25 Hz), low (LF = 0.25-0.75 Hz) and high frequency (HF = 0.75-2.5 Hz) bands. BRS was assessed by means of linear regression between changes of PI and SAP induced by vasoactive drugs or calculation of α-index, a spontaneous BRS index. Key findings: There was no difference in baseline PI or SAP between ovariectomized and sham SHR. Spectral analysis of heart rate variability suggested a shift of sympatho-vagal balance toward sympathetic predominance in ovariectomized SHR (LF/HF = 1.8 ± 0.2 versus 0.7 ± 0.2 in sham SHR, p <0.05). Ovariectomy increased total variance and VLF power of SAP in SHR (29.1 ± 9.6 mmHg2 and 18.6 ± 6.3 mmHg2 versus 9.1 ± 2.1 mmHg2 and 4.3 ± 1.4 mmHg2, respectively, in sham SHR, p <0.05). In addition, ovariectomy reduced reflex bradycardia in SHR (0.18 ± 0.03 ms/mmHg versus 0.34 ± 0.06 ms/mmHg in sham SHR, p <0.05). Ovariectomy did not affect heart rate and SAP variability or BRS in WKY. Significance: These data showed that ovarian hormones deprivation induced marked changes on cardiovascular control, increasing SAP variability and cardiac sympatho-vagal balance and blunting BRS in female hypertensive animals, which reinforce the possible protective role of ovarian hormones on the cardiovascular system.

Original languageEnglish
Pages (from-to)719-724
Number of pages6
JournalLife Sciences
Volume84
Issue number21-22
DOIs
Publication statusPublished - May 22 2009

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Keywords

  • Arterial pressure variability
  • Baroreflex
  • Estrogen
  • Heart rate variability
  • Power spectral analysis
  • SHR

ASJC Scopus subject areas

  • Pharmacology, Toxicology and Pharmaceutics(all)
  • Biochemistry, Genetics and Molecular Biology(all)

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