Commentary on “The role of the large airways on smooth muscle contraction in asthma”

Abstract

LETTERS TO THE EDITORCommentary on “The role of the large airways on smooth muscle contraction in asthma”Riccardo Pellegrino, and Vito BrusascoRiccardo Pellegrino, and Vito BrusascoPublished Online:01 Oct 2007https://doi.org/10.1152/japplphysiol.00684.2007MoreSectionsPDF (28 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat to the editor: Dr. Permutt (3) hypothesizes that the response to constrictor agents in asthma is the result of large-to-medium airways narrowing, leading to a decrease of vital capacity (VC) and, in turn, of 1-s forced expiratory volume (FEV1). The fall in VC could be due to an increase in residual volume (RV), unless total lung capacity (TLC) also increases, thus compensating for the fall in lung function. The hypothesis opens questions that need to be addressed. If it is known that TLC increases with exacerbations (5), its changes with acute administration of bronchoconstrictor or bronchodilator agents are generally regarded as technical artifacts. Perusal of Dr. Brown and colleagues' data (1) reveals that the decrease in TLC after albuterol could be due either to a too high frequency of panting during measurement of thoracic gas volume or, alternatively, to a decrease in lung elastic recoil (Pel). Unfortunately, neither reason for the TLC increase can be ruled out. Against theoretical predictions on flow dynamics, changes in FEV1 failed to correlate with changes in bronchial diameter. Yet this may not be surprising in view of the dependency of FEV1 on thoracic gas compression, Pel, effects of deep breath, and TLC, all of these being affected by disease and medications. Finally, Dr. Permutt's hypothesis on the site of bronchoconstriction in asthma has to be reconciled with the many imaging, functional, and modeling studies suggesting that it is heterogeneous constriction of the distal airways that is central to the disease (2, 4).REFERENCES1 Brown RH, Pearse DB, Pyrgos G, Liu MC, Togias Alkis, Permutt S. The structural basis of airways hyperresponsiveness in asthma. J Appl Physiol 101: 30–39, 2006.Link | ISI | Google Scholar2 Downie SR, Salome CM, Verbanck S, Thompson BR, Berend N, King GG. Ventilation heterogeneity is a major determinant of airway hyperresponsiveness in asthma, independent of airway inflammation. Thorax 2007 [Epub ahead of print].Google Scholar3 Permutt S. The role of the large airways on smooth muscle contraction in asthma. J Appl Physiol; doi:10.1152/japplphysiol.00568.2007.Google Scholar4 Tgavalekos NT, Tawhai M, Harris RS, Musch G, Vidal-Melo M, Venegas JG, Lutchen KR. Identifying airways responsible for heterogeneous ventilation and mechanical dysfunction in asthma: an image functional modeling approach. J Appl Physiol 99: 2388–2397, 2005.Link | ISI | Google Scholar5 Woolcock AJ, Read J. Lung volumes in exacerbations of asthma. Am J Med 41: 259–273, 1966.Crossref | ISI | Google ScholarAUTHOR NOTESAddress for reprint requests and other correspondence: V. Brusasco, Dept. of Internal Medicine, Univ. of Genoa, Respiratory Pathophysiology Unit, Padiglione Maragliano, Ospedale San Martino, Largo R. Benzi, 10, 16132 Genova, Italy (e-mail: [email protected]) Download PDF Previous Back to Top Next FiguresReferencesRelatedInformationCited ByLast Word on Viewpoint “The role of the large airways on smooth muscle contraction in asthma”Solbert Permutt1 October 2007 | Journal of Applied Physiology, Vol. 103, No. 4 More from this issue > Volume 103Issue 4October 2007Pages 1460-1460 Copyright & PermissionsCopyright © 2007 the American Physiological Societyhttps://doi.org/10.1152/japplphysiol.00684.2007PubMed17916684History Published online 1 October 2007 Published in print 1 October 2007 Metrics