Molecular and Clinical Pathological Studies on Atherosclerosis Suppression in the Coronary Artery by Myocardial Bridge.

本文从血管内皮和平滑肌细胞内的血管收缩蛋白和凝血/纤溶蛋白随对LAD血管壁的剪切应力改变表达的角度，探讨了心肌组织覆盖一部分在心外膜脂肪组织内运行的LAD的心肌组织构成的心肌桥（myocardial bridge， MB）抑制动脉粥样硬化的机制。此外，我们还研究了MB的解剖特性，如MB在LAD内的位置以及MB的长度和厚度对LAD血管壁的影响。MB下方的内膜厚度显著低于MB近端和远端。桥段内膜、平滑肌细胞和内膜间质中血管紧张素转换酶明显低于mb近端和远端。除1的结果外，凝血/纤溶蛋白的表达，如组织因子、纤溶酶原激活物-1、组织纤溶酶原激活物在内皮、桥段的平滑肌细胞或内膜基质也明显低于MB近端和远端。1和2的结果表明，由于桥段中这些分子的表达降低，MB段下方的LAD内膜免于动脉粥样硬化的发展。通过分析MB在LAD内的位置、MB的长度、厚度等解剖性质与LAD内膜厚度的关系，MB的解剖性质越长、越厚，MB抑制动脉粥样硬化的作用越大。1,2和3的结果间接说明MB的血管壁受到的剪切应力高于MB近端和远端的LAD节段。

The mechanism of atherosclerosis suppression by myocardial bridge(MB) consisting of myocardial tissue which covers a part of the LAD running in the epicardial adipose tissue has been explored from the viewpoints of vascular constriction proteins and coagulation/fibrinolysis proteins in the vascular endothelium and smooth muscle cells altering their expression in accordance with shear stress against the LAD vascular wall.. In addition, the effects of anatomical properties of MB, such as the location of MB within the LAD as well as the length and thickness of MB, on the LAD vascular wall were histomorphometrically investigated.Results1. Intimal thickness beneath MB was significantly lower than that proximal and distal to MB. Furthermore, The expression of e-nitrogen oxide synthase, endothelin-l.angiotensin converting enzyme in endomelium, smooth muscle cells or intimal stroma in the bridged segment was significantly lower there than that proximal and distal to MB.2. In addition to the results of 1, the expression of coagulation/fibrinolysis proteins, such as tissue factor, plasminogen activator-1, tissue plasminogen activator in endothelium, smooth muscle cells or intimal stroma in the bridged segment was also lower significantly than that proximal and distal to MB. The findings of 1 and 2 indicate that the LAD intima beneath the segment of MB was exempt from atherosclerosis development due to the lowering expression of those molecules at the bridged segment.3. By nalysis on the relationship between the anatomical properties, such as the location of MB within the LAD as well as the kength and thickness of MB, and intimal thickness of the LAD, the longer and thicker the anatomical properties of MB were, the greater the effect of atherosclerosis suppression by MB was. The results of 1, 2 and 3 indirectly illustrate that the vascular wall of MB is stressed with higher shear stress than the LAD segments proximal and distal to MB.