title: Transfer function analysis of ventilatory influence on systemic arterial pressure in the rat.
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 degree for the phase of the lung volume-SAP transfer function over the same frequency range. We conclude that the high-frequency component (0.8-2.4 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 beta-adrenergic system played a major role via its influence on the heart.
authors.affiliation: Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan, Republic of China.
authors.forename: T B
authors.initials: TB
authors.lastname: Kuo
authors.forename: C C
authors.initials: CC
authors.lastname: Yang
authors.forename: S H
authors.initials: SH
authors.lastname: Chan
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001340:Autonomic Nerve Block; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D006323:Heart Arrest / Q000503:physiopathology; D008168:Lung / Q000187:drug effects / Q000502:physiology; D008176:Lung Volume Measurements; D008297:Male; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012119:Respiration / Q000502:physiology*; D012121:Respiration, Artificial; D013318:Stroke Volume; D014628:Vagotomy
chemical_list: D000319:Adrenergic beta-Antagonists; D011433:Propranolol