Sarkadi B, Tordai A, Gárdos G
National Institute of Haematology and Blood Transfusion, Budapest, Hungary.
Biochim Biophys Acta. 1990 Aug 24;1027(2):130-40. doi: 10.1016/0005-2736(90)90076-z.
Jurkat lymphoblasts were stimulated by a monoclonal antibody against the CD3 membrane antigen and the evoked calcium signal was followed by the intracellular fluorescent calcium indicator indo-1. The technique applied allowed us to separately investigate the stimulus-induced intracellular calcium release and the calcium-influx pathways, respectively. In the same cells membrane potential was estimated by the fluorescent dye diS-C3-(5). The resting membrane potential of Jurkat lymphoblasts under normal conditions was between -55 and -60 mV. Membrane depolarization, obtained by increasing external K+ concentration, removing external Cl-, or by increasing the Na+/K+ leak permeability with gramicidin or PCMBS, did not induce calcium influx in the resting cells and did not influence the CD3 receptor-mediated internal calcium release, while strongly inhibited the receptor-mediated calcium influx pathway. Half-maximum inhibition of this calcium influx was observed at membrane potential values of about -35 to -40 mV and this inhibition did not depend on the external calcium concentration varied between 5 and 2500 microM. Membrane hyperpolarization by valinomycin did not affect either component of the calcium signal. The observed selective inhibition of the receptor-operated calcium influx pathway by membrane depolarization is probably an important modulator of calcium-dependent cell stimulation.
用抗CD3膜抗原的单克隆抗体刺激Jurkat淋巴细胞母细胞，并用细胞内荧光钙指示剂indo-1追踪诱发的钙信号。所应用的技术使我们能够分别研究刺激诱导的细胞内钙释放和钙内流途径。在相同的细胞中，用荧光染料diS-C3-(5)估计膜电位。正常条件下Jurkat淋巴细胞母细胞的静息膜电位在-55至-60 mV之间。通过增加细胞外K+浓度、去除细胞外Cl-或用短杆菌肽或对氯汞苯甲酸增加Na+/K+渗漏通透性获得的膜去极化，在静息细胞中不诱导钙内流，也不影响CD3受体介导的细胞内钙释放，而强烈抑制受体介导的钙内流途径。在膜电位约为-35至-40 mV时观察到这种钙内流的半数抑制，并且这种抑制不依赖于5至2500 microM之间变化的细胞外钙浓度。缬氨霉素引起的膜超极化对钙信号的任何一个成分都没有影响。观察到的膜去极化对受体操纵的钙内流途径的选择性抑制可能是钙依赖性细胞刺激的一个重要调节因子。
