title: Respiratory sinus arrhythmia and central respiratory drive in humans.
abstract: 1. The influence of central inspiratory drive on heart rate variability was investigated in young human subjects using power spectral analysis of R-R intervals. 2. The area of the high-frequency component occurring at the respiratory frequency (0.2-0.25 Hz) in the power spectral density curves was used as an index of respiratory sinus arrhythmia. 3. Central inspiratory drive was increased by breathing a CO2-enriched (5%) gas mixture and this condition was compared with a similar degree of ventilation produced voluntarily. 4. Tests were conducted on eight young subjects with and without low-dose scopolamine (scopoderm TTS) in a double-blind cross-over trial. 5. Scopolamine decreased heart rate and increased the high-frequency peak, suggesting that its main action on the cardiac vagal pathway was a peripheral one, possibly increasing the efficacy of vagal impulses on the cardiac pacemaker. 6. With scopolamine, CO2 breathing increased the area of the high-frequency component significantly more than a similar degree of ventilatory movements produced by voluntary hyperventilation. 7. It is concluded that respiratory sinus arrhythmia in humans is at least partly dependent on a central respiratory-cardiac coupling, most probably similar to that shown in animal studies.
authors.affiliation: Department of Physiology, University of Birmingham, U.K.
authors.forename: M
authors.initials: M
authors.lastname: Al-Ani
authors.forename: A S
authors.initials: AS
authors.lastname: Forkins
authors.forename: J N
authors.initials: JN
authors.lastname: Townend
authors.forename: J H
authors.initials: JH
authors.lastname: Coote
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D001146:Arrhythmia, Sinus / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000008:administration & dosage; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology; D007091:Image Processing, Computer-Assisted; D010275:Parasympathetic Nervous System / Q000503:physiopathology*; D010276:Parasympatholytics / Q000494:pharmacology; D012119:Respiration / Q000502:physiology*; D012601:Scopolamine / Q000494:pharmacology
chemical_list: D010276:Parasympatholytics; D002245:Carbon Dioxide; D012601:Scopolamine