Rosskopf D, Morgenstern E, Scholz W, Osswald U, Siffert W
Max-Planck-Institut für Biophysik, Frankfurt/Main, Federal Republic of Germany.
J Hypertens. 1991 Mar;9(3):231-8.
Accumulating evidence suggests an increased activity of the Na(+)-H+ exchanger in essential hypertension. The present investigation aimed at developing a test for routine measurements. Platelet-rich plasma was added directly to a cuvette placed into an aggregometer containing 140 mmol/l sodium propionate medium (pH 6.7, 37 degrees C). The accumulation of intracellular sodium due to activation of Na(+)-H+ exchange results in an osmotic cell swelling, which is detectable as a decrease in optical density (OD). This reaction reflects activation of the Na(+)-H+ exchanger since we observed (1) a dose-dependent inhibition by amiloride (inhibition constant, Ki = 10 mumol/l) and ethylisopropylamiloride (Ki = 0.07 mumol/l) and (2) a dependence on extracellular sodium of the OD changes. Electron microscopy of sodium propionate-treated platelets revealed a general swelling and a distinct decrease in electron density of the cytosol without other significant alterations. Quantification of Na(+)-H+ exchange activities was accomplished by calculating rate constants of the recorded changes in OD. Application of this assay to 20 essential hypertensives and 32 normotensives demonstrated an increased activity of the Na(+)-H+ exchanger in essential hypertensives (rate constants 29.8 x 10(-3) per s versus 21.7 x 10(-3) per s).
越来越多的证据表明，原发性高血压患者的钠氢交换体活性增强。本研究旨在开发一种用于常规测量的检测方法。将富含血小板的血浆直接加入置于含有140 mmol/l丙酸钠培养基（pH 6.7，37℃）的凝集仪中的比色杯中。由于钠氢交换激活导致的细胞内钠积累会引起渗透性细胞肿胀，这可通过光密度（OD）降低来检测。该反应反映了钠氢交换体的激活，因为我们观察到：（1）氨氯地平（抑制常数，Ki = 10 μmol/l）和乙基异丙基氨氯地平（Ki = 0.07 μmol/l）呈剂量依赖性抑制；（2）OD变化依赖于细胞外钠。对丙酸钠处理的血小板进行电子显微镜检查发现，细胞普遍肿胀，胞质电子密度明显降低，无其他明显改变。通过计算记录的OD变化的速率常数来定量钠氢交换活性。将该检测方法应用于20例原发性高血压患者和32例血压正常者，结果显示原发性高血压患者的钠氢交换体活性增强（速率常数分别为29.8×10⁻³每秒和21.7×10⁻³每秒）。
