title: Reflex decrease of histamine-induced bronchoconstriction after laryngeal stimulation in humans.
abstract: The aim of this work was to determine whether the nonadrenergic, noncholinergic, inhibitory nervous system can be reflexly activated in humans by laryngeal stimulation. The stimulation was achieved with a cytology brush passed through a bronchoscope previously introduced transnasally and positioned just above the epiglottis. In one series of experiments, subjects were premedicated with beta-adrenergic and cholinergic blockers, and bronchoconstriction was induced by histamine inhalation. The results showed that mechanical irritation of the vocal cords with the cytology brush produced a sharp, short-lasting (less than 1 min) decrease in RL from (mean +/- SE) 6.8 +/- 2.1 to 4.8 +/- 1.5 cm H2O.L-1.s, and in the absence of parasympathetic blockade, laryngeal irritation produced a fall in RL from (mean +/- SE) 9.0 +/- 3.7 to 5.4 +/- 2.0 cm H2O.L-1.s (p less than 0.0001) (ANOVA). This decrease in RL was independent of the slight cough produced by laryngeal stimulation and reflects a change in lower and not upper airway resistance. Adequacy of the beta-adrenergic and cholinergic blockade was checked with an intravenous infusion of isoproterenol and inhaled methacholine, respectively. In 2 subjects, the fall in RL was abolished by a block of the superior laryngeal nerves and direct local anesthesia of the vocal cords. We conclude that mechanical irritation of the larynx produces a partial reversal of histamine-induced bronchoconstriction that is mediated through nervous pathways that are neither beta-adrenergic nor cholinergic in origin. We suggest that this decrease in bronchoconstriction is modulated by the nonadrenergic, noncholinergic, inhibitory nervous system.
mesh_terms: D000328:Adult; D000403:Airway Resistance; D001341:Autonomic Nervous System / Q000502:physiology*; D001985:Bronchial Provocation Tests; D001986:Bronchial Spasm / Q000139:chemically induced* / Q000209:etiology; D003371:Cough / Q000209:etiology; D005260:Female; D006632:Histamine; D006801:Humans; D007823:Laryngeal Nerves / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D010812:Physical Stimulation; D012018:Reflex / Q000502:physiology*
chemical_list: D006632:Histamine