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Adenosine 5'-monophosphate challenge elicits a more peripheral airway response than methacholine challenge.
MedLine Citation:
PMID:  21393472     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Background: Adenosine 5'-monophosphate (AMP) and methacholine are commonly used to assess airway hyperreactivity. However, it is not fully known whether the site of airway constriction primarily involved during challenges with either agent is similar. Objective: Using a ventilation distribution test, we investigated whether the constriction induced by each agent involves the lung periphery in a similar fashion. Methods: Ventilation distribution was evaluated by the phase III (S) slope of the single-breath washout, using gases with different diffusivities like helium (He) and hexafluorosulfur (SF(6)). A greater post-challenge increase in S(He) reflects alterations at the level of terminal and respiratory bronchioles, while a greater increase in S(SF6) reflects alterations in alveolar ducts, increases to an equal extent reflecting alterations in more proximal airways where gas transport is still convective for both gases. S(SF6), S(He) were measured in 15 asthma patients before and after airway challenges (20% FEV(1) fall) with AMP and methacholine. Results: S(He) increased to a greater extent than S(SF6) after AMP challenge (5.7 vs 3.7%.l(-1); p=0.002), with both slopes increasing to an equal extent after methacholine challenge (3.1%.l(-1); p=0.959). Conclusions: The larger increase in S(He) following AMP challenge suggests distal ventilation impairment up to the level of terminal and respiratory bronchioles. With methacholine the similar increases in S(He) and S(SF6) suggests a less distal impairment. AMP, therefore, seems to impact more extensively the very peripheral airways, whereas methacholine seems to have an effect on less distal airways.
Authors:
Alain Michils; Yvon Elkrim; Amaryllis Haccuria; Alain Van Muylem
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-3-10
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  -     ISSN:  1522-1601     ISO Abbreviation:  -     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-3-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1Erasme University Hospital.
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