title: Parasympathetic Stimuli on Bronchial and Cardiovascular Systems in Humans.
abstract: BACKGROUND
  It is not known whether parasympathetic outflow simultaneously acts on bronchial tone and cardiovascular system waxing and waning both systems in parallel, or, alternatively, whether the regulation is more dependent on local factors and therefore independent on each system. The aim of this study was to evaluate the simultaneous effect of different kinds of stimulations, all associated with parasympathetic activation, on bronchomotor tone and cardiovascular autonomic regulation.
  
  
  METHODS
  Respiratory system resistance (Rrs, forced oscillation technique) and cardio-vascular activity (heart rate, oxygen saturation, tissue oxygenation index, blood pressure) were assessed in 13 volunteers at baseline and during a series of parasympathetic stimuli: O2 inhalation, stimulation of the carotid sinus baroreceptors by neck suction, slow breathing, and inhalation of methacholine.
  
  
  RESULTS
  Pure cholinergic stimuli, like O2 inhalation and baroreceptors stimulation, caused an increase in Rrs and a reduction in heart rate and blood pressure. Slow breathing led to bradycardia and hypotension, without significant changes in Rrs. However slow breathing was associated with deep inhalations, and Rrs evaluated at the baseline lung volumes was significantly increased, suggesting that the large tidal volumes reversed the airways narrowing effect of parasympathetic activation. Finally inhaled methacholine caused marked airway narrowing, while the cardiovascular variables were unaffected, presumably because of the sympathetic activity triggered in response to hypoxemia.
  
  
  CONCLUSIONS
  All parasympathetic stimuli affected bronchial tone and moderately affected also the cardiovascular system. However the response differed depending on the nature of the stimulus. Slow breathing was associated with large tidal volumes that reversed the airways narrowing effect of parasympathetic activation.
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Zannin
authors.affiliation: Allergologia e Fisiopatologia Respiratoria, ASO S. Croce e Carle, Cuneo, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Pellegrino
authors.affiliation: Dipartimento di Medicina Interna, Università di Pavia e IRCCS Policlinico S. Matteo, Pavia, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Di Toro
authors.affiliation: Allergologia e Fisiopatologia Respiratoria, ASO S. Croce e Carle, Cuneo, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Antonelli
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy.
authors.forename: Raffaele L
authors.initials: RL
authors.lastname: Dellacà
authors.affiliation: Folkhälsan Institute of Genetics, Folkhälsan Research Center, Biomedicum Helsinki, Helsinki, Finland.
authors.forename: Luciano
authors.initials: L
authors.lastname: Bernardi
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D001980:Bronchi / Q000187:drug effects* / Q000502:physiology; D002319:Cardiovascular System / Q000187:drug effects* / Q000378:metabolism; D004562:Electrocardiography; D005260:Female; D064368:Healthy Volunteers; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism; D010276:Parasympatholytics / Q000494:pharmacology*; D011311:Pressoreceptors / Q000737:chemistry / Q000378:metabolism; D012119:Respiration
chemical_list: D010276:Parasympatholytics; D016210:Methacholine Chloride; D010100:Oxygen