Effects of direct cedrol inhalation into the lower airway on autonomic nervous activity in totally laryngectomized subjects.
BACKGROUND
Relationships between smell sensation and autonomic changes have been studied extensively. However, the possibility that odorants may also act on the lung and lower airway remains unknown.


CONCLUSIONS
The present results provide the first evidence that the lung and lower airway exert an inhibitory influence on the cardiovascular system in response to Cedrol (odorant) in the air under physiological conditions.


OBJECTIVE
Previous studies reported that Cedrol (odorant) inhalation (CI) induced changes in autonomic balance and baroreceptor sensitivity (BRS) in both healthy subjects and anosmic patients. This suggests that Cedrol may act on the lower airway, and that the pulmonary system may exert an inhibitory influence on the cardiovascular system.


METHODS
To test the above possibility, vaporized Cedrol (64.0 +/- 7.7 10(-9)m) or blank air was directly inhaled through the lower airway from a hole in the trachea, but not through the upper airway, using totally laryngectomized subjects. During the experiment, ECG, systolic (SBP) and diastolic (DBP) blood pressures were measured. Sympathetic and parasympathetic nervous activity was estimated by spectral analyses of variability in these parameters (heart rate variability (HRV), SBP variability (SBPV) and DBP variability (DBPV)). BRS was computed from transfer gain between SBP and the R-R interval of the ECG.


RESULTS
SBP and DBP significantly decreased during CI, although there were no significant differences in HR and respiratory rate. BRS significantly increased during CI. The low frequency components of SBPV and DBPV (indices for sympathetic activity) significantly decreased during CI, while high frequency components of HRV (an index for parasympathetic activity) significantly increased.


CONCLUSIONS
The present experiment using totally laryngectomized patients replicated the similar results in healthy subjects who inhaled Cedrol through the nose, suppression of sympathetic outflow and increase in parasympathetic outflow. These results demonstrated that Cedrol acts on the lower airway and pulmonary system, and suggest a new target for drug therapy of hypertension.
Umeno
Katsumi
K
System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan.
Hori
Etsuro
E
Tsubota
Masahito
M
Shojaku
Hideo
H
Miwa
Takaki
T
Nagashima
Yoshinao
Y
Yada
Yukihiro
Y
Suzuki
Toshiyuki
T
Ono
Taketoshi
T
Nishijo
Hisao
H
D000280:Administration, Inhalation; D000368:Aged; D001341:Autonomic Nervous System / Q000187:drug effects* / Q000502:physiology; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007825:Laryngectomy; D008168:Lung / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D000081223:Polycyclic Sesquiterpenes; D013729:Terpenes / Q000008:administration & dosage*
D000081223:Polycyclic Sesquiterpenes; D013729:Terpenes; C078669:cedrol