Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, QC, Canada H3A 2B2.
J Biomech. 2012 Jul 26;45(11):1916-23. doi: 10.1016/j.jbiomech.2012.05.027. Epub 2012 Jun 13.
Solute transport phenomena mediate many aspects of the physiology and contrast agent-based clinical imaging of articular cartilage. Temperatures up to 10°C below standard body temperature (37°C) are common in articulating joints during normal activities and clinically (e.g. cold treatment of injuries). Therefore it is of interest to characterize the effects of temperature changes on solute transport parameters in cartilage. A range of fluorescent solutes including fluorescein isothiocyanate, 4 and 40kDa dextrans, myoglobin, insulin and chondroitin sulfate were prepared and used in assays of solute effective partition coefficient and effective diffusivity in bovine intermediate zone articular cartilage explants maintained at 10, 22 or 37°C. Trends for increasing partition coefficient with increasing temperature were evident for all solutes except chondroitin sulfate, with significant changes between 22 and 37°C for 4kDa dextran, insulin and myoglobin. Diffusivities of most solutes tested also tended to increase with increasing temperature, with significant changes between 10 and 22°C for FITC, 40kDa dextran and myoglobin. Oddly, insulin diffusivity decreased significantly as temperature increased from 22 to 37°C while chondroitin sulfate diffusivity exhibited no clear temperature dependence. These results highlight solute-specific temperature dependences of transport phenomena which may depend upon molecular weight, chemical structure, molecular conformation, and solute-matrix and solute-solute interactions. The articular cartilage explants themselves exhibited small but significant changes in water and glycosaminoglycan contents during experiments, underscoring the importance of solute-matrix interactions. Solute transport parameters in cartilage and their temperature dependences are therefore not easily predicted, and case-by-case experimental determination may be essential.
溶质传输现象介导了关节软骨生理学和对比剂为基础的临床成像的许多方面。在正常活动中和临床上（例如受伤的冷疗），关节中的温度通常比标准体温（37°C）低 10°C 左右。因此，研究温度变化对软骨中溶质传输参数的影响具有重要意义。我们制备了一系列荧光溶质，包括荧光素异硫氰酸酯、4 和 40kDa 葡聚糖、肌红蛋白、胰岛素和硫酸软骨素，并用于研究在 10°C、22°C 和 37°C 下保持的牛中间区关节软骨外植体中溶质有效分配系数和有效扩散率的变化。除硫酸软骨素外，所有溶质的分配系数都随温度升高而升高，4kDa 葡聚糖、胰岛素和肌红蛋白在 22°C 和 37°C 之间的变化显著。大多数测试的溶质的扩散系数也随温度升高而增加，FITC、40kDa 葡聚糖和肌红蛋白在 10°C 和 22°C 之间的变化显著。奇怪的是，胰岛素的扩散系数随着温度从 22°C 升高到 37°C而显著降低，而硫酸软骨素的扩散系数则没有明显的温度依赖性。这些结果突出了溶质特异性的传输现象的温度依赖性，这可能取决于分子量、化学结构、分子构象以及溶质-基质和溶质-溶质相互作用。在实验过程中，关节软骨外植体本身的水和糖胺聚糖含量也发生了微小但显著的变化，这突显了溶质-基质相互作用的重要性。因此，软骨中的溶质传输参数及其温度依赖性不易预测，可能需要逐个案例进行实验确定。
