Related Experiment Videos
Transfer function analysis of ventilatory influence on systemic arterial pressure in the rat
1Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan, Republic of China.
The American Journal of Physiology
|November 1, 1996
Summary
The respiratory system influences systemic arterial pressure (SAP) fluctuations, particularly at higher frequencies. The autonomic nervous system, especially beta-adrenergic activity, amplifies this mechanical effect at lower frequencies via cardiac modulation.
Area of Science:
- Cardiovascular Physiology
- Respiratory Mechanics
- Autonomic Nervous System Regulation
Background:
- Systemic arterial pressure (SAP) exhibits fluctuations influenced by various physiological mechanisms.
- The interplay between respiratory mechanics and autonomic nervous system (ANS) modulation of cardiovascular function requires further elucidation.
Purpose of the Study:
- To investigate the hypothesis that respiratory pumping influences SAP fluctuations.
- To determine the modulatory role of the ANS, particularly cardiac influence, on this respiratory-induced SAP variability.
Main Methods:
- Mechanical ventilation (0-3 Hz) was applied to anesthetized and paralyzed Sprague-Dawley rats.
- Coherence between lung volume and SAP signals was analyzed across different ventilatory frequencies.
- Pharmacological agents (phentolamine, propranolol, atropine) and bilateral vagotomy were used to assess ANS contributions.
Main Results:
- High coherence between lung volume and SAP was observed between 0.5-2.5 Hz, unaffected by most interventions.
- Propranolol significantly reduced lung volume-SAP transfer function magnitude (0.5-1.5 Hz) and altered phase.
- Bilateral vagotomy had no discernible effect on the lung volume-SAP relationship.
Conclusions:
- The respiratory pumping mechanism generates high-frequency SAP components (0.8-2.4 Hz).
- The ANS, specifically the beta-adrenergic system acting on the heart, amplifies the lower-frequency mechanical influence of respiration on SAP.