Horowitz S B, Paine P L, Tluczek L, Reynhout J K
Biophys J. 1979 Jan;25(1):33-44. doi: 10.1016/S0006-3495(79)85276-5.
A method is described for the quantitative determination of free and bound solute concentrations in the cytoplasm of intact cells. The method includes (a) introduction of a gelatin gel reference phase (RP) into the cytoplasm; (b) diffusion of dissolved substances between cytoplasm and RP, (c) cell quenching to - 196 degrees C to prevent subsequent solute redistributions, (d) ultra-low temperature microdissection to isolate RP and cytoplasm samples, and (e) analysis of isolates for solute and water content. In normal oocytes of the salamander, Desmognathus ochrophaeus, free or RP Na+ and K+ are 21.0 +/- 1.1 and 128.8 +/- 2.4 mu eq/ml, respectively, and vary stoichiometrically in altered oocytes. Overall cytoplasmic concentrations are 75.2 +/- 2.7 mu eq Na+/ml and 88.6 +/- 1.5 mu eq K+/ml. Cytoplasmic chemical activities are 16.2 mu eq Na+/ml and 99.2 mu eq K+/ml, corresponding to activity coefficients of 0.22 and 1.12, respectively. The results demonstrate unambiguously that (a) oocytes actively transport Na+ and K+, and (b) cytoplasm has important binding properties which differentiate it from an ordinary aqueous solution. These cytoplasmic properties are investigated in the following paper.
本文描述了一种定量测定完整细胞胞质中游离和结合溶质浓度的方法。该方法包括：(a) 将明胶凝胶参考相 (RP) 引入胞质；(b) 溶解物质在胞质和RP之间扩散；(c) 将细胞骤冷至 -196℃ 以防止随后的溶质重新分布；(d) 超低温显微切割以分离RP和胞质样品；(e) 分析分离物的溶质和水分含量。在蝾螈Desmognathus ochrophaeus的正常卵母细胞中，游离或RP中的Na⁺和K⁺分别为21.0±1.1和128.8±2.4 μeq/ml，并且在改变的卵母细胞中化学计量变化。胞质总浓度为75.2±2.7 μeq Na⁺/ml和88.6±1.5 μeq K⁺/ml。胞质化学活性分别为16.2 μeq Na⁺/ml和99.2 μeq K⁺/ml，相应的活度系数分别为0.22和1.12。结果明确表明：(a) 卵母细胞主动转运Na⁺和K⁺；(b) 胞质具有重要的结合特性，这使其有别于普通水溶液。这些胞质特性将在下文进行研究。
