TITLE:
Discrimination between upper versus lower airway components to the rise of total airway resistance measured by Pennock’s method after nasal irritant challenge
AUTHORS:
Zuzana Biringerova, Silvia Gavliakova, Eva Hanuskova, Tomas Buday, Jana Plevkova
KEYWORDS:
Airways; Resisatnce; In Vivo; Pennock’s Method
JOURNAL NAME:
Open Journal of Molecular and Integrative Physiology,
Vol.3 No.3,
August
28,
2013
ABSTRACT:
Terminals of the trigeminal
afferents innervating nasal mucosa are called gate keepers, since these fibres
detect substances entering the airways. Trigeminal excitation by irritants
initiates airway defensive mechanisms, and it is also attributed to the
influence of lower airways resistance in a term of nasobronchial reflex. This
phenomenon is frequently under debate, because some investigators were unable
to confirm its existence. The aim of our study was to determine, whether
pharmacological approach could be useful to reach high accuracy and better
interpretation of the data obtained by Pennock’s method. Pennock’s method,
which is frequently used to measure airway resistance in vivo (Raw) in fact measures total airway resistance, however,
the data are usually interpreted in a terms of bronchomotor response. The upper
airway component, which represents
approximately 40% of Raw, is commonly not considered as being important
in this method. 30 Dunkin Hartley guinea pigs were exposed to nasal stimuli
(TRPA1 agonist—irritant allylisothiocyanate (10 mM,
AITC), TRPM8 agonist with cooling potential menthol (10-3 M) and saline as a control). Raw was measured pre
challenge as baseline, after nasal provocation and further, after nasal
inhalation of histamine and methacholine (10-6 M) each. The data showed rise of Raw only after nasal
AITC challenge, with further increased responsiveness to histamine and
methacholine (5.3 vs 10.18 vs 11.26 vs 17.32 cmH2O.s-1, p 0.05). No
significant changes were detected after saline, or menthol respectively. Data
obtained in further experiment and its analysis showed that pre-treatment with
nasal administration of 1% oxymetazoline but without salbutamol inhalation
prevented the rise of Raw after nasal irritant
challenges. Raw after nasal irritant challenges rises rather due to
nasal response than due to narrowing of the lower airways.