Na-Ca exchange in ferret red blood cells.
Na-Ca exchange in ferret red blood cells.
复制标题
雪貂红细胞中的钠钙交换。
DOI：
10.1152/ajpcell.1989.256.2.c390
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Milanick,MA
中科院分区：
文献类型：
--
作者：
Milanick,MA
雪貂有高钠（140毫摩尔/升）红细胞。为了确定雪貂红细胞是否存在Na-Ca交换系统，必须抑制Na + K + 2Cl共转运体的Na外排和Ca泵的Ca外排。这是通过用硝酸盐代替细胞中的氯化物和用抑制钙泵的钒酸盐装载细胞来实现的。在这些条件下，细胞外钠（Naout）抑制钙内流。大量钙内流需要细胞内钠（Nain），因为用Li取代Na使钙内流降低到不到原始速率的十分之一。Caout将Na的外流刺激了大约两倍。缺钠细胞的Ca外排从0.8 mmol增加到3.2 mmol。Naout的存在使l -1 - h-1细胞堆积。细胞置于无na溶液中积累Ca：细胞内总Ca比游离Ca高20倍。Ca离子载体A23187的加入释放了大部分Ca。由于Na梯度驱使净Ca上坡，所以Na和Ca的通量是耦合的。在无钠溶液中，Ca内流的K1/2通常约为10微米（偶尔约为100微米），最大流速（Vmax）为1.5-4.4 mmol。L填充细胞-1 - h-1。在约= 150 mM时，K1/2增加了5- 150倍。在一些细胞中，Naout使Vmax降低了大约四倍，这表明Naout并不总是与Caout竞争。（摘要删节250字）
Ferrets have high Na (140 mmol/l) red blood cells. To determine whether ferret red cells had a Na-Ca exchange system, Na effluxes via the Na + K + 2Cl cotransrpoter and Ca effluxes via the Ca pump had to be inhibited. This was accomplished by replacing cell chloride with nitrate and by loading the cells with vanadate that inhibits the Ca pump. Under these conditions, extracellular Na (Naout) inhibited Ca influx. Intracellular Na (Nain) was required for the large Ca influx as replacement of Na with Li reduced Ca influx to less than one-tenth of the original rate. Caout stimulated Na efflux by about twofold. The Ca efflux from cells depleted of Na was increased from 0.8 to 3.2 mmol.l packed cells-1.h-1 by the presence of Naout. Cells placed in a Na-free solution accumulated Ca: total intracellular Ca was 20-fold higher than free Caout. Most of this Ca was released on addition of the Ca ionophore, A23187. Because the Na gradient had driven net Ca uphill, the fluxes of Na and Ca are coupled. In a Na-free solution, the K1/2 for Ca influx was usually approximately 10 microM (occasionally approximately 100 microM), and the maximal velocity (Vmax was 1.5-4.4 mmol.l packed cells-1.h-1. At Naout = 150 mM, K1/2 increased 5- to 150-fold. In some cells, Naout decreased Vmax by approximately fourfold, suggesting that Naout does not always compete with Caout.(ABSTRACT TRUNCATED AT 250 WORDS)