Mapp C E, Chitano P, De Marzo N, Di Blasi P, Saetta M, Di Stefano A, Bosco V M, Allegra L, Fabbri L M
Institute of Occupational Medicine, University of Padua, Italy.
J Appl Physiol (1985). 1989 Oct;67(4):1331-5. doi: 10.1152/jappl.1989.67.4.1331.
Contractility of tracheal smooth muscle strips and spiral strips of fourth to fifth generation bronchi was studied in organ baths. The relationship among contractility, airway smooth muscle myosin, and smooth muscle thickness was also examined. The trachea was divided into three segments, each consisting of 12-14 rings. Smooth muscle strips from each of the three regions (top, middle, and bottom of the trachea) and from fourth to fifth generation bronchi were studied. Acetylcholine (ACh) sensitivity (-log EC50) was 8.1, 7.1, 7.9, and 6.1 for the top, middle, and bottom of the trachea and the bronchi, respectively. At P = 0.01, the EC50 ACh value of the top of the trachea differed from the EC50 value of the bronchi. Maximal tension (Tmax) generated in bronchi (3.2 g) was lower (P less than 0.01) than in the top (10.4 g), middle (7.1 g), and bottom of the trachea (5.1 g). Differences between trachea and bronchi disappeared when Tmax was corrected for smooth muscle myosin content. Thickness of smooth muscle in bronchi was less (P less than 0.01) than in the three regions of trachea. Tmax was significantly correlated with airway smooth muscle thickness (r = 0.56; P less than 0.05). These results suggest that in mongrel dogs sensitivity to ACh shows a gradient from the top of the trachea to the bronchi and that Tmax is greater in the trachea than in the bronchi and is significantly correlated with thickness of smooth muscle.
在器官浴槽中研究了气管平滑肌条以及第四至第五代支气管的螺旋条的收缩性。还检测了收缩性、气道平滑肌肌球蛋白和平滑肌厚度之间的关系。将气管分为三个节段，每个节段由12 - 14个环组成。研究了来自气管三个区域（气管顶部、中部和底部）以及第四至第五代支气管的平滑肌条。气管顶部、中部、底部以及支气管对乙酰胆碱（ACh）的敏感性（-log EC50）分别为8.1、7.1、7.9和6.1。在P = 0.01时，气管顶部的ACh EC50值与支气管的EC50值不同。支气管产生的最大张力（Tmax）（3.2 g）低于气管顶部（10.4 g）、中部（7.1 g）和底部（5.1 g）（P < 0.01）。当对Tmax进行平滑肌肌球蛋白含量校正后，气管和支气管之间的差异消失。支气管平滑肌厚度小于气管的三个区域（P < 0.01）。Tmax与气道平滑肌厚度显著相关（r = 0.56；P < 0.05）。这些结果表明，在杂种犬中，对ACh的敏感性从气管顶部到支气管呈梯度变化，并且气管中的Tmax大于支气管中的Tmax，且与平滑肌厚度显著相关。
