Biomaterial Database

Airway smooth muscle in asthma. 1996

J L Black, and P R Johnson

Department of Pharmacology, University of Sydney, NSW, Australia. judblack@pharmacol.su.oz.au

One of the factors that may contribute to the exaggerated airway narrowing in asthma is an abnormality of the airway smooth muscle. This abnormality could take the form of an increase in the amount of muscle or an alteration in its pharmacological reactivity. The former could be due to either hypertrophy (an increase in individual muscle cell size) or hyperplasia (an increase in cell number). Changes in pharmacological reactivity that could be relevant to altered airway calibre could result from an increase in contraction or alternatively, a decrease in relaxation. Based on available evidence, the increase in smooth muscle bulk is probably the consequence of both hyperplasia and hypertrophy and several growth factors, inflammatory mediators and cytokines have been implicated. Asthmatic airway tissue is rarely available for in vitro pharmacological studies and evidence for enhanced contraction is limited. Recent evidence suggests that an abnormality in beta adrenoceptor function may contribute to impairment of relaxation, but further work needs to be done. Passive sensitization of non-asthmatic airways in vitro provides a good model for the study of the mechanisms underlying airway hyperresponsiveness, and will be the subject of more intensive study in the future.

UI	MeSH Term	Description	Entries
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009126	Muscle Relaxation	That phase of a muscle twitch during which a muscle returns to a resting position.	Muscle Relaxations,Relaxation, Muscle,Relaxations, Muscle
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D001980	Bronchi	The larger air passages of the lungs arising from the terminal bifurcation of the TRACHEA. They include the largest two primary bronchi which branch out into secondary bronchi, and tertiary bronchi which extend into BRONCHIOLES and PULMONARY ALVEOLI.	Primary Bronchi,Primary Bronchus,Secondary Bronchi,Secondary Bronchus,Tertiary Bronchi,Tertiary Bronchus,Bronchi, Primary,Bronchi, Secondary,Bronchi, Tertiary,Bronchus,Bronchus, Primary,Bronchus, Secondary,Bronchus, Tertiary
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000402	Airway Obstruction	Any hindrance to the passage of air into and out of the lungs.	Choking,Airway Obstructions,Obstruction, Airway,Obstructions, Airway
D001249	Asthma	A form of bronchial disorder with three distinct components: airway hyper-responsiveness (RESPIRATORY HYPERSENSITIVITY), airway INFLAMMATION, and intermittent AIRWAY OBSTRUCTION. It is characterized by spasmodic contraction of airway smooth muscle, WHEEZING, and dyspnea (DYSPNEA, PAROXYSMAL).	Asthma, Bronchial,Bronchial Asthma,Asthmas
D016535	Bronchial Hyperreactivity	Tendency of the smooth muscle of the tracheobronchial tree to contract more intensely in response to a given stimulus than it does in the response seen in normal individuals. This condition is present in virtually all symptomatic patients with asthma. The most prominent manifestation of this smooth muscle contraction is a decrease in airway caliber that can be readily measured in the pulmonary function laboratory.	Bronchial Hyperreactivities,Hyperreactivities, Bronchial,Hyperreactivity, Bronchial