Transfer function analysis of ventilatory influence on systemic arterial pressure in the rat

Terry B.J. Kuo, Cheryl C.H. Yang, Samuel H.H. Chan

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

We evaluated the hypothesis that fluctuations in systemic arterial pressure (SAP) are under the influence of the respiratory pumping mechanism subjected to a modulatory action by the autonomic nervous system that is exerted primarily on the heart. Computer-generated broad-band mechanical ventilation (0-3 Hz) was applied to Sprague-Dawley rats that were anesthetized with ketamine and paralyzed with pancuronium. We observed excellent coherence between lung volume and SAP signals at ventilatory rates between 0.5 and 2.5 Hz; this coherence was unaffected by phentolamine, propranolol, atropine, bilateral vagotomy, or ventilatory stroke volume at 2- 4 ml. Whereas bilateral vagotomy exerted no discernible effect, propranolol elicited a significant frequency-dependent (0.5-1.5 Hz) reduction in the magnitude of lung volume-SAP and lung volume-pulse pressure transfer functions. There was also a shift toward 0° for the phase of the lung volume-SAP transfer function over the same frequency range. We conclude that the high-frequency component 10.8-2.4 Hz) of the SAP spectrum may be generated by the respiratory pumping mechanism. However, the lower-frequency end of this mechanical influence is subjected to additional amplification by the autonomic nervous system, in which the β-adrenergic system played a major role via its influence on the heart.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume271
Issue number5 40-5
Publication statusPublished - Nov 1996
Externally publishedYes

Keywords

  • β- adrenergic modulation
  • auto- and cross-spectra
  • broad-band mechanical ventilation
  • coherence
  • lung volume
  • magnitude and phase of transfer function
  • pulse pressure

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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