Changes in ADC caused by tensile loading of rabbit Achilles tendon: Evidence for water transport
Changes in ADC caused by tensile loading of rabbit Achilles tendon: Evidence for water transport
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DOI：
10.1006/jmre.2000.2075
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发表时间：
2000-06-01
影响因子：
2.2
通讯作者：
Sotak, CH
中科院分区：
文献类型：
--
作者：
Han, S;Gemmell, SJ;Sotak, CH
在静态拉伸载荷和未加载状态下对兔跟腱进行水扩散测量。沿沿着两个方向：平行于肌腱长轴和垂直于肌腱长轴测量表观扩散系数（ADC）。肌腱在以两种方式制备后进行研究：（a）在磷酸盐缓冲盐水（PBS）中冷冻储存后和（B）新鲜分离后。在所有肌腱的ADC中观察到统计学显著的方向各向异性。与肌腱长轴平行方向的ADC值明显大于垂直方向。各向异性归因于水分子在垂直方向上受到的更大限制，并且与肌腱的已知几何形状一致。在PBS中储存导致肌腱肿胀。这增加了沿沿着两个方向测量的ADC，并降低了各向异性。ADC中各向异性的存在与样品在磁体中的取向无关。ADC增加沿着两个方向施加5 N的拉伸载荷后，增加是最大的沿着肌腱的垂直轴。为了确定ADC的负荷相关变化是否反映了原纤维间距的变化，我们使用电子显微镜来测量原纤维间距的负荷相关变化。与负荷相关的纤维间距变化不能解释ADC的变化。加载引起的ADC增加归因于肌腱水沿肌腱外表面沿着挤出成体相。在PBS储存的样品中，挤出了足够的流体，可以使其可视化。还研究了ADC对5 N拉伸载荷的瞬态响应。在两个方向上的绝对ADC随着加载而增加，并且在卸载时恢复到基线。ADC的瞬态变化，加载和卸载，有一个平均时间常数约为15分钟。负载引起的瞬态ADC的变化的幅度是可比的静态加载实验中看到的。(C)北京大学出版社.
Water diffusion measurements were performed on rabbit Achilles tendons during static tensile loading and tendons in an unloaded state. The apparent diffusion coefficient (ADC) was measured along two directions: parallel and perpendicular to the long axis of the tendon. Tendons were studied after being prepared in two ways: (a) after being stored frozen in phosphate-buffered saline (PBS) and (b) freshly isolated. Statistically significant directional anisotropy was observed in the ADC in all tendons. The ADC was significantly greater in the direction parallel to the long axis of the tendon than in the perpendicular direction. The anisotropy is attributed to the greater restrictions seen by the water molecules in the perpendicular direction and is consistent with the known geometry of the tendon. Storage in PBS caused tendons to swell. This increased the ADC measured along both directions and reduced the anisotropy. The existence of anisotropy in the ADC was not related to the orientation of the specimen in the magnet. The ADC increased along both directions following the application of a 5-N tensile load; the increase was greatest along the perpendicular axis of the tendon. In order to determine whether load-related changes in the ADC reflected changes in interfibrilar spacing, we used electron microscopy to measure load-related changes in fibril spacing. Load-related changes in fiber spacing could not account for the observed changes in the ADC. The increase in ADC caused by loading was attributed to the extrusion of tendon water into a bulk phase along the outside surface of the tendon. In PBS-stored samples, enough fluid was extruded that it could be visualized. The transient response of the ADC to a 5-N tensile load was also studied. The absolute ADC in both directions increased with loading and recovered to baseline upon unloading. The transient changes in ADC, for both loading and unloading, had a mean time constant of approximately 15 min. The magnitude of the load-induced transient ADC changes was comparable to that seen in the static-loading experiments. (C) 2000 Academic Press.