严重烧伤早期心肌细胞骨架损伤的力学研究

Mechanical Study on Myocardial Cytoskeleton Damage in Early Stage of Severe Burn Injury

目的旨在了解严重烧伤早期心肌生物力学特性的变化及细胞骨架损伤对心肌细胞粘弹力学特性的影响。方法在体实验，测定大鼠严重烧伤后（２４小时内）心肌力学的变化，同时采用流式细胞术定量分析心肌细胞骨架蛋白的动态变化。离体心肌细胞培养，采用免疫组化及流式细胞术观察心肌细胞骨架蛋白分布和含量变化，并通过微管吸吮实验测定心肌细胞粘弹力学特性变化。结果烧伤后早期，左心室收缩压（ＬＶＳＰ）、左心室内压上升最大速率（＋ｄｐ／ｄｔｍａｘ）、左心室内压下降最大速率（－ｄｐ／ｄｔｍａｘ）、心力环总面积（ＬＯ）显著下降（Ｐ＜０．０１），左心室舒张末期压（ＬＶｅｄｐ）升高（Ｐ＜０．０５或Ｐ＜０．０１）。心肌细胞骨架蛋白Ｖｉｎｃｕｌｉｎ、Ｄｅｓｍｉｎ、β－Ｔｕｂｕｌｉｎ平均荧光强度明显降低（Ｐ＜０．０１）。缺氧、烧伤血清可引起心肌细胞骨架结构破坏及重构，网络结构消失，细胞完整性破坏；心肌细胞弹性系数Ｋ１、Ｋ２及粘性系数μ下降（Ｐ＜０．０５或Ｐ＜０．０１）。结论大鼠严重烧伤后早期，细胞骨架结构破坏及重构可能是心肌细胞不可逆损伤的早期征象，细胞骨架损伤决定性影响心肌细胞被动粘弹力学特性，心肌顺应性降低。

Aim To study the changes of myocardial biomechanical properties and the effect of cytoskeleton damage on the viscoelastic properties of myocardial cells in the early stage of burn injury. Methods In vivo, the changes of myocardial mechanics were measured by invasive method, and the myocardial cytoskeletal proteins were analyzed by flow cytometer (FCM). In vitro myocardial cell culture, the distribution and the content change of the myocardial cytoskeleton were observed by immunocytochemistry technique and FCM, and the viscoelastic properties of myocardial cells were measured by micropipette aspiration experiment. Results In the early stage of burn injury, the left ventricular systolic pressure (LVSP), +dp/dtmax, -dp/dtmax, LO decreased (P<0.01), and the left ventricular enddiastolic pressure (LVEDP) increased (P<0.05 or P<0.01). The mean fluorescence intensity of myocardial cytoskeletal proteins, Vinculin, Desmin, and βTubulin decreased (P<0.01). Hypoxia and burned serum could result in the myocardial cytoskeleton damage, and pathological remodeling, therefore cytoskeletal network disappeared, and cell integrity damaged. The viscoelastic coefficients of myocardial cell decreased (P<0.05 or P<0.01). Conclusions The study demonstrates that in the early stage of severe burn injury, the damage and pathological remodeling of myocardial cytoskeleton might be an early sign of irreversible injury. The alteration of myocardial cytoskeleton affects vitally the passive viscoelastic biomechanic properties, and results in myocardial compliance decrease.