Opazo Saez Anabelle M, Schellenberg R Robert, Ludwig Mara S, Meiss Richard A, Paré Peter D
UBC Pulmonary Research Laboratory, St Paul's Hospital, Vancouver, BC, Canada.
Can J Physiol Pharmacol. 2002 Sep;80(9):865-71. doi: 10.1139/y02-112.
We have observed striking differences in the mechanical properties of airway smooth muscle preparations among different species. In this study, we provide a novel analysis on the influence of tissue elastance on smooth muscle shortening using previously published data from our laboratory. We have found that isolated human airways exhibit substantial passive tension in contrast to airways from the dog and pig, which exhibit little passive tension (<5% of maximal active force versus approximately 60% for human bronchi). In the dog and pig, airway preparations shorten up to 70% from Lmax (the length at which maximal active force occurs), whereas human airways shorten by only approximately 12% from Lmax. Isolated airways from the rabbit exhibit relatively low passive tension (approximately 22% Fmax) and shorten by 60% from Lmax. Morphologic evaluation of airway cross sections revealed that 25-35% of the airway wall is muscle in canine, porcine, and rabbit airways in contrast to approximately 9% in human airway preparations. We postulate that the large passive tension needed to stretch the muscle to Lmax reflects the high connective tissue content surrounding the smooth muscle, which limits shortening during smooth muscle contraction by imposing an elastic load, as well as by causing radial constraint.
我们观察到不同物种气道平滑肌制剂的力学特性存在显著差异。在本研究中，我们利用实验室先前发表的数据，对组织弹性对平滑肌缩短的影响进行了新颖的分析。我们发现，与犬和猪的气道相比，分离出的人类气道表现出显著的被动张力，犬和猪的气道几乎没有被动张力（最大主动力的<5%，而人类支气管约为60%）。在犬和猪中，气道制剂从Lmax（产生最大主动力的长度）缩短达70%，而人类气道仅从Lmax缩短约12%。兔的分离气道表现出相对较低的被动张力（约22%Fmax），并从Lmax缩短60%。气道横截面的形态学评估显示，犬、猪和兔气道壁的25 - 35%是肌肉，而人类气道制剂中约为9%。我们推测，将肌肉拉伸至Lmax所需的大量被动张力反映了平滑肌周围结缔组织含量高，这通过施加弹性负荷以及引起径向约束来限制平滑肌收缩期间的缩短。
