Grodzinsky A J
Crit Rev Biomed Eng. 1983;9(2):133-99.
This review has dealt primarily with the electromechanical and transport properties of the extracellular matrix, which generally contains ionized charged groups under physiological conditions. Connective tissues are not electrically "active" in the sense of nerve or muscle; that is, electrical signals do not propagate as waves within the tissue. However, we have attempted to show the importance of "passive" electromechanical coupling and the coupling of passive transport mechanisms to the functional health of connective tissues. The effect of mechanical and electrical stresses on cell growth and biosynthesis is a relatively new and exciting area of research that should provide important clues concerning the interactions between cells and the extracellular matrix. While the role of cells in connective tissues is beyond the scope of this review, it is well known that environmental stresses have a direct effect on the structure and composition of connective tissues. Studies have shown that changes in the chemical and mechanical environment of cells can significantly alter cell synthesis of polysaccharide and protein components of the matrix. For example, Gillard et al. studied the glycosaminoglycan and collagen composition of the flexor digitorium profundus tendon of the rabbit. In regions where the tendon is subject to tensile forces, the tissue GAG content is approximately 0.2% of the dry weight, a value not unlike other tendons. However, in the small sesamoid region where the tendon hooks around the heel bone, the tendon is subjected to high compressional stresses. In this region, the GAG concentration is 15 to 20 times higher and the GAG composition is similar to that of articular cartilage. Gillard et al. found that manipulation of the tendon so as to release the compressional forces lead to a decrease in GAG content by more than 60%. Subsequent replacement of the tendon to its original position caused a concomitant increase in the GAG content. These results can be interpreted to be directly linked to the influence of mechanical forces on cell synthesis. The recent finding that cell synthesis is also affected by imposed electrical fields may suggest that electrical, mechanical and chemical signals are somehow interpreted by the cells along common pathways. The fact that electrical potentials are naturally produced near cells by deformation of the extracellular matrix provides additional support for such hypotheses.
本综述主要探讨了细胞外基质的机电特性和传输特性，在生理条件下，细胞外基质通常含有离子化的带电基团。从神经或肌肉的角度来看，结缔组织并非电“活性”组织；也就是说，电信号不会在组织内以波的形式传播。然而，我们试图展示“被动”机电耦合以及被动传输机制与结缔组织功能健康之间耦合的重要性。机械应力和电应力对细胞生长和生物合成的影响是一个相对较新且令人兴奋的研究领域，它应该能为细胞与细胞外基质之间的相互作用提供重要线索。虽然细胞在结缔组织中的作用超出了本综述的范围，但众所周知，环境应力对结缔组织的结构和组成有直接影响。研究表明，细胞化学和机械环境的变化会显著改变细胞对基质多糖和蛋白质成分的合成。例如，吉拉德等人研究了兔趾深屈肌腱的糖胺聚糖和胶原蛋白组成。在肌腱承受拉力的区域，组织中糖胺聚糖含量约为干重的0.2%，这一数值与其他肌腱并无不同。然而，在肌腱绕过跟骨的小籽骨区域，肌腱承受着高压缩应力。在该区域，糖胺聚糖浓度高出15至20倍，且糖胺聚糖组成与关节软骨相似。吉拉德等人发现，对肌腱进行操作以释放压缩力会导致糖胺聚糖含量下降超过60%。随后将肌腱恢复到原始位置会使糖胺聚糖含量随之增加。这些结果可以解释为与机械力对细胞合成的影响直接相关。最近发现细胞合成也会受到外加电场的影响，这可能表明电、机械和化学信号在某种程度上是由细胞沿着共同途径进行解读的。细胞外基质变形会在细胞附近自然产生电势这一事实为这类假说提供了额外支持。
