Volume increase in growth plate chondrocytes during hypertrophy: The contribution of organic osmolytes
Volume increase in growth plate chondrocytes during hypertrophy: The contribution of organic osmolytes
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DOI：
10.1016/s8756-3282(01)00710-4
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发表时间：
2002-04-01
期刊：
影响因子：
4.1
通讯作者：
Urban, JPG
中科院分区：
文献类型：
--
作者：
Farnum, CE;Lee, R;Urban, JPG
在生长板软骨细胞的分化级联过程中，细胞体积增加多达10-15倍。这种体积增加，这发生在不同程度的生长板生长在不同的速度，已被证明是一个最重要的变量，在理解定量方面的细胞动力学的长骨生长。我们的假设是，这种体积增加，这是通过细胞肿胀的水吸胀，需要通过激活或上调膜转运机制的渗透压物质的细胞内积累。无机渗透调节剂（如Na+、K+和Cl-）的显著细胞内蓄积可能破坏正常细胞代谢，而有机渗透调节剂的细胞内蓄积被认为与代谢功能更相容。因此，我们集中在确定的有机渗透剂甜菜碱，氨基酸，肌醇和山梨醇的体积增加的贡献。提取幼牛生长板的合并低温恒温切片，然后自动分析其氨基酸含量。甜菜碱和糖醇的分析是通过萃取和衍生化，然后通过高效液相色谱法（HPLC）。平行体视学分析将渗透压变化与软骨细胞分化阶段相关联，特别是比较增殖与肥大软骨细胞中的细胞内浓度和量。计算表明，最大限度地，这些有机渗透剂，总共占细胞内渗透剂的6%-7%，需要维持体积的增加，最显着的贡献是从甜菜碱。这表明，细胞内积累的有机渗透不是一个主要的策略使用的生长板软骨细胞在其终末分化的体积增加。这些数据还表明，这些渗透调节剂的转运蛋白存在差异调节，使得细胞内浓度随着细胞通过分化级联而不断改变。(Bone 30：574-581，2002）（C）2002由Elsevier Science Inc. All rights reserved.
During the differentiation cascade of growth plate chondrocytes, cells undergo as much as a 10-15-fold increase in volume. This volume increase, which occurs to different extents in growth plates growing at different rates, has been demonstrated to be the single most significant variable in understanding the quantitative aspects of the cellular kinetics of long bone growth. Our hypothesis is that this volume increase, which occurs through cell swelling by water imbibition, requires intracellular accumulation of osmolytes through activation or upregulation of membrane transport mechanisms. Significant intracellular accumulation of inorganic osmolytes, such as Na+, K+, and Cl-, is potentially disruptive to normal cellular metabolism, whereas intracellular accumulation of organic osmolytes is considered to be more compatible with metabolic function. Thus, we concentrated on determining the contributions of organic osmolytes-betaine, amino acids, inositol, and sorbitol-to volume increase. Pooled cryostat sections of young bovine growth plates were extracted followed by automated analysis for their content of amino acids. Analysis for betaine and the sugar alcohols was done by extraction and derivatization, followed by high-performance liquid chromatography (HPLC). Parallel stereological analyses correlated osmolyte changes to stages of chondrocytic differentiation, specifically comparing intracellular concentration and amount in proliferative vs. hypertrophic chondrocytes. Calculations demonstrated that, maximally, these organic osmolytes, in total, account for 6%-7% of the intracellular osmolytes required to sustain the volume increase, and that the most significant contribution is from betaine. This suggests that intracellular accumulation of organic osmolytes is not a primary strategy used by growth plate chondrocytes during volume increase of their terminal differentiation. The data also suggest that there is a differential regulation or transporters of these osmolytes such that intracellular concentrations are constantly modified as cells proceed through the differentiation cascade. (Bone 30:574-581, 2002) (C) 2002 by Elsevier Science Inc. All rights reserved.