Effect of resting smooth muscle length on contractile response in resistance airways.
Effect of resting smooth muscle length on contractile response in resistance airways.
复制标题
静息平滑肌长度对阻力气道收缩反应的影响。
DOI：
10.1152/jappl.1987.62.2.711
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Leff,AR
中科院分区：
文献类型：
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作者：
Shioya,T;Munoz,NM;Leff,AR
我们在18只杂种狗体内使用钽支气管造影研究了静息平滑肌长度对主要阻力气道（0-5代）收缩反应的影响。在每次给药后，通过钽支气管造影重复静脉推注给药，生成10（-10）至10（-7）mol/kg乙酰甲胆碱（MCh）的剂量-反应曲线[在功能残气量（FRC）下]。气道收缩随剂量等效刺激而发生显着变化，并且从气管（气道直径变化8.8 +/- 2.2%）到第五代支气管（49.8 +/- 3.0%; P小于0.001）依次变化。为每个气道生成长度-张力曲线以确定气道直径（即，静息原位平滑肌长度），此时使用静脉推注10（-8）mol/kg MCh引起最大收缩。获得了每个气道的Frank-Starling关系;引起最大收缩的经肺压从气管的2.50 +/- 1.12 cmH 2 O（约FRC）逐渐增加到第五代气道的18.3 +/- 1.05 cmH 2 O（约50% TLC）（P <0.001）。将气道直径的变化绘制成气道半径的函数时，得到了类似的关系。我们证明了肺体积的巨大异质性，在最大的收缩引起和拟副交感神经收缩的分布在阻力支气管的前几代。我们的数据还表明，肺过度充气可能会导致气道收缩反应增强，向最佳的静息平滑肌长度转移的静息平滑肌长度。
We studied the effect of resting smooth muscle length on the contractile response of the major resistance airways (generations 0–5) in 18 mongrel dogs in vivo using tantalum bronchography. Dose-response curves to 10(-10) to 10(-7) mol/kg methacholine (MCh) were generated [at functional residual capacity (FRC)] by repeated intravenous bolus administration using tantalum bronchography after each dose. Airway constriction varied substantially with dose-equivalent stimulation and varied sequentially from trachea (8.8 +/- 2.2% change in airway diam) to fifth-generation bronchus (49.8 +/- 3.0%; P less than 0.001). Length-tension curves were generated for each airway to determine the airway diameter (i.e., resting in situ smooth muscle length) at which maximal constriction was elicited using bolus intravenous injection of 10(-8) mol/kg MCh. A Frank-Starling relationship was obtained for each airway; the transpulmonary pressure at which maximal constriction was elicited increased progressively from 2.50 +/- 1.12 cmH2O for trachea (approximately FRC) to 18.3 +/- 1.05 cmH2O for fifth-generation airways (approximately 50% TLC) (P less than 0.001). A similar relationship was obtained when change in airway diameter was plotted as a function of airway radius. We demonstrate substantial heterogeneity in the lung volumes at which maximal constriction is elicited and in distribution of parasympathomimetic constriction within the first few generations of resistance bronchi. Our data also suggest that lung hyperinflation may lead to augmented airway contractile responses by shifting resting smooth muscle length toward optimum resting smooth muscle length.