使用停流装置测量人红细胞中的氯-碳酸氢根交换。

Chloride-bicarbonate exchange in human red cells measured using a stopped flow apparatus.

Lambert A, Lowe A G

J Physiol. 1980 Sep;306:431-43. doi: 10.1113/jphysiol.1980.sp013405.

Abstract

A new stopped-flow apparatus has been used to measure the exchange of intracellular chloride and extracellular bicarbonate across the human erythrocyte membrane at 37 degrees C. 2. The concentration dependence of the activation of the anion exchange system by extracellular bicarbonate was consistent with the existence of a saturable membrane-carrier. Analysis of the results assuming Michaelis--Menten kinetics indicated a Vmax for chloride--bicarbonate exchange of 73 . 4 +/- 14 . 4 mol. (3 x 10(13) cells.min)-1 and Km for bicarbonate of 11 . 1 +/- 2 . 8 mM at 37 degrees C (pH 7 . 1). 3. Correction of the directly computed values of Vmax for incomplete saturation of the carrier by intracellular chloride and the inhibitory effects of intracellular bicarbonate and extracellular chloride gave a Vmax of 157 +/- 43 . 8 mol (3 x 10(13) cells.min)-1 and a Km of 15 . 5 +/- 5 . 2 mM-bicarbonate at 37 degrees C. 4. Comparison of Vmax obtained at 37 and 10 degrees C indicates that the activation energy for chloride--bicarbonate exchange in this temperature range is 18 . 7 --19 . 6 kcal.mol-1 depending on whether corrected or uncorrected values are used. 5. Extracellular furosemide inhibited chloride--bicarbonate exchange with a KI of 0 . 12 microM assuming competition between furosemide and bicarbonate and 0 . 17 microM assuming non-competitive inhibition. 6. Extracellular chloride also inhibited chloride--bicarbonate exchange but the kinetics of inhibition were complex.

摘要

一种新型的停流装置已被用于在37℃下测量细胞内氯离子与细胞外碳酸氢根离子跨人红细胞膜的交换。2. 细胞外碳酸氢根离子对阴离子交换系统激活的浓度依赖性与存在可饱和的膜载体相一致。假设符合米氏动力学对结果进行分析表明，在37℃（pH 7.1）时，氯离子 - 碳酸氢根离子交换的Vmax为73.4±14.4 mol·(3×10¹³个细胞·分钟)⁻¹，碳酸氢根离子的Km为11.1±2.8 mM。3. 通过对载体未被细胞内氯离子完全饱和以及细胞内碳酸氢根离子和细胞外氯离子的抑制作用对直接计算得到的Vmax值进行校正后，在37℃时Vmax为157±43.8 mol·(3×10¹³个细胞·分钟)⁻¹，碳酸氢根离子的Km为15.5±5.2 mM。4. 对在37℃和10℃时获得的Vmax进行比较表明，在此温度范围内，氯离子 - 碳酸氢根离子交换的活化能为18.7 - 19.6 kcal·mol⁻¹，具体取决于使用的是校正值还是未校正值。5. 假设速尿与碳酸氢根离子之间存在竞争，细胞外速尿抑制氯离子 - 碳酸氢根离子交换的KI为0.12 μM；假设为非竞争性抑制，KI为0.17 μM。6. 细胞外氯离子也抑制氯离子 - 碳酸氢根离子交换，但抑制动力学较为复杂。