Oral Presentations - Pathology and Laboratory Medicine - University ...

Graduate StudentLeslie YM Chin 1,4 , Ynuk Bossé 4 , Dennis Solomon 4 , Tillie L Hackett 3,4 , Peter D.Paré 2,4 , and Chun Y. Seow 1,41Departments of Pathology and Laboratory Medicine, 2 Medicine, and 3 Anesthesiology,Pharmacology and TherapeuticsAbstract # 66Leslie Chinmechanical properties of asthmatic airway smoothmuscle revisitedBackround/ObjectivesAirway smooth muscle (ASM) is the major downstream effector of the excessive airway narrowing which ischaracteristic of asthma. Excessive airway narrowing could be related to changes in ASM force, shortening, velocityand/or length adaptability. These properties have been studied in different animal species but data on human tissue aresparse. For example, the force-velocity relationship and length adaptation have yet to be elucidated in human ASM.MethodsASM strips from human tracheas were mounted in a myograph capable of measuring force and length simultaneously.Ca2+ free-saline solution relaxed the tissue, for estimation of in situ length (Lref). Measurements performed included:force at different muscle lengths (before and after length-adaptation), velocity at different loads (early and late phasesof contraction), isometric force recovery after oscillatory length perturbation and maximal shortening from Lref.ResultsHuman airway smooth muscle showed significant length adaptation at short and long lengths. Asthmatic ASMdemonstrated reduced force adaptation at 50% Lref, increased shortening velocity at low loads, and increasedresistance to an oscillatory strain.ConclusionThe impaired bronchodilating response to deep inspiration seen in asthmatics may be an innate property of the airwaysmooth muscle itself, independent of the non-muscle components of teh airway wall or lung parenchyma.Poster Presentations * 2 0 1 077