Nguyen B L, Thompson J S, Quigley E M
Surgical Service Omaha VAMC, Nebraska, USA.
Dig Dis Sci. 1995 Jul;40(7):1491-7. doi: 10.1007/BF02285197.
Our aim was to investigate the contribution of variations in intestinal muscle morphology or function to regional differences in motor properties in vivo. We quantitated intestinal muscle thickness and surface area along the canine gut and compared the in vitro contractile properties of the jejunum and ileum. The thickness and cross-sectional surface area of both circular and longitudinal muscle demonstrated a parabolic distribution along the intestine, with the greatest values occurring in the proximal and distal regions. The terminal ileum had the greatest circular (885 +/- 194 microns) and longitudinal muscle (367 +/- 135 microns) thickness. Circular muscle was 2.5-3 times thicker than longitudinal muscle at all points. Passive tension was similar in muscle strips from the mid-jejunum, mid-ileum, and terminal ileum (2.8 +/- 0.8, 2.5 +/- 0.4, and 2.3 +/- 0.8 vs 2.5 +/- 0.5, 1.9 +/- 0.5, and 2.8 +/- 1.0, longitudinal and circular, respectively). Active and total tension, however, were significantly greater in longitudinal than circular muscle in mid-jejunum (active; 8.5 +/- 1.4 vs 5.6 +/- 1.2, P < 0.05 and total 11.3 +/- 1.7 vs 8.1 +/- 1.2) and in mid-ileum (active 9.5 +/- 1.6 vs 5.8 +/- 1.2 and total 12.0 +/- 1.6 vs 7.7 +/- 1.2). Values for each layer were similar in both sites. In contrast, in the terminal ileum, longitudinal and circular muscle strips demonstrated similar active (10.1 +/- 1.7 vs 9.0 +/- 2.7, NS) and total tension (12.4 +/- 2.0 vs 11.9 +/- 3.4, NS). Dose-response curves to carbachol (10(-8)-10(-2) M) were similar in all these regions. We conclude (1) there are regional variations in muscle mass but contractile properties are similar in jejunum and ileum; and (2) the unique motor properties of the terminal ileum may be related more to differences in muscle morphology and neural input than intrinsic function.
我们的目的是研究肠道肌肉形态或功能的变化对体内运动特性区域差异的影响。我们对犬类肠道沿线的肠道肌肉厚度和表面积进行了定量，并比较了空肠和回肠的体外收缩特性。环形肌和纵行肌的厚度和横截面积沿肠道呈抛物线分布，最大值出现在近端和远端区域。回肠末端的环形肌（885±194微米）和纵行肌（367±135微米）厚度最大。在所有部位，环形肌比纵行肌厚2.5至3倍。空肠中段、回肠中段和回肠末端的肌条被动张力相似（纵行肌和环形肌分别为2.8±0.8、2.5±0.4和2.3±0.8对2.5±0.5、1.9±0.5和2.8±1.0）。然而，空肠中段纵行肌的主动张力和总张力显著大于环形肌（主动张力：8.5±1.4对5.6±1.2，P<0.05；总张力：11.3±1.7对8.1±1.2），回肠中段也是如此（主动张力9.5±1.6对5.8±1.2，总张力12.0±1.6对7.7±1.2）。两个部位各层的值相似。相比之下，在回肠末端，纵行肌和环形肌条的主动张力（10.1±1.7对9.0±2.7，无显著性差异）和总张力（12.4±2.0对11.9±3.4，无显著性差异）相似。所有这些区域对卡巴胆碱（10⁻⁸ - 10⁻² M）的剂量反应曲线相似。我们得出结论：（1）肌肉质量存在区域差异，但空肠和回肠的收缩特性相似；（2）回肠末端独特的运动特性可能更多地与肌肉形态和神经输入的差异有关，而非内在功能。
