Influence of stimulation of nasal afferents on expiration reflex evoked from vocal folds.
Cough and sneezing are upregulated during the upper airway diseases, most likely to enhance airway defense. The aim of this study was to assess the expiration reflex (ER), another expulsive defensive airway reflex, during allergic rhinitis (AR) and intranasal (i.n.) capsaicin challenge. Thirty male guinea pigs, sensitized to ovalbumin were used in the study. They were divided into 3 groups of 10 animals each: AR group (i.n. ovalbumin), capsaicin group (i.n. capsaicin 50 microM, 15 microl), and controls without any challenge. The animals were anesthetized with urethane (1.1 mg/kg) and allowed to breath spontaneously via tracheostomy. Metal canula was introduced into the right hemithorax to assess intrapleural pressure. ER was elicited by mechanical stimulation of the vocal folds using a thin nylon loop introduced upwards via tracheostomy. Maximal expiratory effort of ER (MEE) and the count of post-ER laryngeal coughs were evaluated. Mechanical stimulation of the vocal folds in controls produced isolated ER. They were followed by post-ER cough only in 11% of provocations. AR and capsaicin challenge increased MEE compared with that in controls (P<0.05). In these two groups of animals, the ER was followed by post ER-cough in 75% of provocations. The count of post-ER coughs in the group order control/AR/capsaicin was 0-2/2-4/1-3, respectively; P<0.05). The ER from the vocal folds is upregulated in a similar manner as is cough and sneeze. The central neuronal mechanisms are proposed to mediate this effect, but the spread of inflammation from upper airways to the larynx, verified histologically in the present study, may contribute as well.
Department of Pathophysiology, Comenius University, Jessenius Faculty of Medicine, Martin, Slovakia. plevkova@jfmed.uniba.sk
J
J
Plevkova
J
J
Antosiewicz
I
I
Poliacek
M
M
Adamkov
J
J
Jakus
K
K
Svirlochova
M
M
Tatar
D000818:Animals; D002211:Capsaicin / Q000633:toxicity; D045853:Exhalation / Q000187:drug effects / Q000502:physiology*; D006168:Guinea Pigs; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D010812:Physical Stimulation / Q000379:methods; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D006255:Rhinitis, Allergic, Seasonal / Q000139:chemically induced / Q000503:physiopathology; D014827:Vocal Cords / Q000187:drug effects / Q000294:innervation*
D002211:Capsaicin