Sarkadi B, Grinstein S, Rothstein A, Gárdos G
Acta Biochim Biophys Acad Sci Hung. 1985;20(3-4):193-202.
A method is described which allows studying specific cation transport pathways of the cell membranes by converting ion fluxes into volume changes. Lipophilic weak electrolytes, such as propionate, rapidly penetrate the cell membranes in their undissociated acid from but not as negatively charged ions. When human red cells are incubated in isoosmotic K-propionate media an intracellular acidification occurs with a limited propionate uptake and volume increase (corresponding to the buffering capacity of the cytoplasm). If both protons and alkali cations are rendered permeable, a rapid salt influx and volume increase is observed. The latter can be quantitatively followed by electronic sizing methods. A detailed characterization of the system is provided through studies with ionophores, inhibitors of the red cell anion exchange system and drugs which activate or inhibit the Ca2+-induced K+ transport. It is demonstrated that in K-propionate media the permeability of the Ca2+-induced K+ pathway can be directly estimated. The method is suitable to observe population (all-or-none) responses in the activation of the K+ pathway under certain experimental conditions. The application of the method in the search for cation-proton exchanger systems is discussed and its use for demonstration purposes by producing selective lysis of red cells is described.
本文描述了一种方法，该方法通过将离子通量转化为体积变化来研究细胞膜的特定阳离子转运途径。亲脂性弱电解质，如丙酸盐，以未解离的酸形式而非带负电荷的离子形式迅速穿透细胞膜。当人红细胞在等渗的钾丙酸盐培养基中孵育时，会发生细胞内酸化，丙酸盐摄取有限且体积增加（对应于细胞质的缓冲能力）。如果质子和碱金属阳离子都具有通透性，就会观察到快速的盐流入和体积增加。后者可以通过电子筛分方法进行定量跟踪。通过使用离子载体、红细胞阴离子交换系统抑制剂以及激活或抑制钙诱导钾转运的药物进行研究，对该系统进行了详细表征。结果表明，在钾丙酸盐培养基中，可以直接估算钙诱导钾途径的通透性。该方法适用于在某些实验条件下观察钾途径激活中的群体（全或无）反应。讨论了该方法在寻找阳离子 - 质子交换器系统中的应用，并描述了其通过产生红细胞选择性裂解用于演示目的的用途。
