title: Effects of slow, controlled breathing on baroreceptor control of heart rate and blood pressure in healthy men.
abstract: BACKGROUND
  Slow, controlled breathing has been shown by cross-spectral techniques to potentiate arterial baroreflex control of heart rate. However, crucial aspects of the effects of slow breathing on the arterial baroreflex remain unsettled, namely whether the major function of the arterial baroreflex (i.e. the control of blood pressure) is also potentiated and whether baroreflex function is differentially modulated according to the age of the individual.
  
  
  OBJECTIVE
  To examine the bradycardic and depressor responses to selective carotid baroreceptor stimulation by the neck chamber technique (-15 and -30 mmHg neck suction) and the cross-spectral R-R interval/systolic blood pressure relationship (alpha index).
  
  
  METHODS
  In 24 resting, supine healthy male volunteers (aged 19-66 years, mean +/-SEM 37.5 +/- 3.19 years), blood pressure (Finapres), R-R interval (electrocardiogram) and ventilation (impedance) were recorded continuously. Both assessments were performed during spontaneous breathing and during 6 cycles/min controlled ventilation in random order.
  
  
  RESULTS
  The depressor and bradycardic responses to neck suction were significantly larger during slow breathing than in spontaneous breathing (+32 and +85%, respectively; both P < 0.01). The alpha index was also significantly larger during slow breathing (+62%; P < 0.01). Even after the volunteers were divided into older (> 50 years, n = 9) and younger (< 30 years, n = 9) groups, the baroreflex potentiation related to slow breathing was clearcut and significant for both the depressor (+46 and +24% older and younger volunteers; both P < 0.01) and the bradycardic (+130 and +73% older and younger volunteers; both P < 0.01) responses. When the assessment was made by computing the cross-spectral alpha index, a marked potentiation related to slow breathing was observed in younger volunteers (+99%; P < 0.01), whereas in older volunteers only a trend to an enhancement (by 32%; P < 0.055) was observed.
  
  
  CONCLUSIONS
  Slow controlled breathing is associated with potentiation of both the depressor and the cardio-inhibitory components of the arterial baroreflex, the potentiation being largely similar regardless of the age of the individual.
authors.affiliation: Divisione di Cardioriabilitazione, Ospedale di Seregno, Azienda Ospedaliera Vimercate, Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Radaelli
authors.forename: Roberta
authors.initials: R
authors.lastname: Raco
authors.forename: Paola
authors.initials: P
authors.lastname: Perfetti
authors.forename: Andrea
authors.initials: A
authors.lastname: Viola
authors.forename: Arianna
authors.initials: A
authors.lastname: Azzellino
authors.forename: Maria G
authors.initials: MG
authors.lastname: Signorini
authors.forename: Alberto U
authors.initials: AU
authors.lastname: Ferrari
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D002346:Carotid Sinus / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009333:Neck; D015656:Respiratory Mechanics / Q000502:physiology*; D013396:Suction; D016683:Supine Position