Effect of l-menthol on laryngeal receptors.
We have studied the effect of l-menthol on laryngeal receptors. Experiments have been conducted in 11 anesthetized dogs that breathed through a tracheostomy. We have recorded the activity of 23 laryngeal cold receptors and 19 mechanoreceptors. Constant flows of air, 15-50 ml/s (low) and 100-150 ml/s (high), passing for 10 s through the isolated upper airway in the expiratory direction, lowered laryngeal temperature and activated the cold receptors. This cold-induced discharge promptly ceased upon withdrawal of the airflow. Addition of l-menthol to the airflow evoked, for a similar decrease in temperature, a greater peak activation of the cold receptors than airflow alone (low flows 164%, high flows 111%); statistical significance was reached only for the lower flow. This activity outlasted the cessation of airflow by 30-120 s, even at a time when laryngeal temperature had returned to control (low flow 237%, high flow 307% of similar trials with airflow alone). Four laryngeal cold receptors were also tested with l-menthol added to a warm, humidified airflow that did not change laryngeal temperature; all of them were stimulated with a long-lasting discharge. Nine cold receptors were also tested with d-neomenthol and d-isomenthol; both isomers stimulated the receptors. None of the 19 mechano-receptors tested was affected by l-menthol. We conclude that l-menthol constitutes a specific stimulant of laryngeal cold receptors and could provide a useful tool for the study of their reflex effects.
Sant'Ambrogio
F B
FB
Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77550-2774.
Anderson
J W
JW
Sant'Ambrogio
G
G
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D003080:Cold Temperature; D004285:Dogs; D005260:Female; D007823:Laryngeal Nerves / Q000187:drug effects / Q000502:physiology; D007830:Larynx / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008465:Mechanoreceptors / Q000187:drug effects / Q000502:physiology; D008610:Menthol / Q000494:pharmacology*; D011984:Sensory Receptor Cells / Q000187:drug effects* / Q000502:physiology
D008610:Menthol