CALCIUM DIFFUSION-COEFFICIENT IN MYXICOLA AXOPLASM
CALCIUM DIFFUSION-COEFFICIENT IN MYXICOLA AXOPLASM
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DOI：
10.1016/0143-4160(95)90088-8
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发表时间：
1995-06-01
期刊：
影响因子：
4
通讯作者：
ABERCROMBIE, RF
中科院分区：
文献类型：
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作者：
ALBALDAWI, NF;ABERCROMBIE, RF
钙扩散系数测定Myxicola轴浆和琼脂对照两个独立的技术：一个利用Ca-45，和一个利用钙特异性微电极。用微电极技术在具有完整的钙定序细胞器的轴质中测得最低值，约为0.1 × 10 ~（-6）cm ~（2）·s ~（-1）。用同位素和微电极技术测得ATP耗尽的轴浆的扩散系数为0.5-2 × 10 ~（-6）cm ~（2）·s ~（-1）。在无细胞器的轴质中，蛋白质浓度大约是完整轴质的一半，在0.7 μ M Ca时测得的扩散系数为1.4-3 × 10（-6）cm（2）·s（-1），在3-5 μ M Ca时测得的扩散系数为7 × 10（-6）cm（2）·s（-1）。当与钙缓冲能力[Al-Baldawi NF. Abercrombie RF.（1995）用Nitr-5和DM-硝基酚测定细胞质Ca缓冲能力。Cell Calcium，17，409-422]，这些扩散系数要求部分缓冲容量位于移动的Ca结合位点上。
Calcium diffusion coefficients were measured in Myxicola axoplasm and in agar controls by two independent techniques: one utilizing Ca-45, and one utilizing Ca-specific mini-electrodes. The lowest value, similar to 0.1 x 10(-6) cm(2).s(-1) was measured, using the mini-electrode technique, in axoplasm with intact Ca-sequenstering organelles. With ATP-depleted axoplasm, diffusion coefficients of 0.5-2 x 10(-6) cm(2).s(-1) were obtained by both isotope and mini-electrode techniques. In organelle-free axoplasm with a protein concentration roughly half that in the intact axoplasm, diffusion coefficients of 1.4-3 x 10(-6) cm(2).s(-1) were measured at 0.7 mu M Ca and 7 x 10(-6) cm(2).s(-1) at 3-5 mu M Ca. When compared with measurements of the calcium buffering capacity [Al-Baldawi NF. Abercrombie RF. (1995) Cytoplasmic Ca buffer capacity determined with Nitr-5 and DM-nitrophen. Cell Calcium, 17, 409-422], these diffusion coefficients require that part of the buffer capacity be located on mobile Ca-binding sites.