Effects of intracellular free Ca and rate of Ca influx on the Ca pump.
Effects of intracellular free Ca and rate of Ca influx on the Ca pump.
复制标题
细胞内游离 Ca 和 Ca 内流速率对 Ca 泵的影响。
DOI：
10.1152/ajpcell.1989.256.6.c1138
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Yingst,DR
中科院分区：
文献类型：
--
作者：
Yang,YC;Yingst,DR
本文研究了人红细胞钙泵活性与细胞内游离钙(FCaI)的关系。用琼脂糖柱层法制成重新密封的幽灵，除包含其他成分外，还包括小于0.1微米的FCAI，100微米的偶氮唑III，以及1 mM的ATP加上ATP再生系统(主动幽灵)或不添加ATP和不含再生系统的再生系统(被动幽灵)。通过将这些幽灵悬浮在含有不同组合的游离钙(1-30微米)和钙离子载体A23187(0.1-0.7微米)的溶液中来控制这些幽灵的钙内流速度。进入钙可增加活动性幽灵的FCAI值，并刺激泵。在被动幽灵中，所有的钙运动都可以用一个速率常数来描述。根据主动幽灵的净钙摄取率，利用被动幽灵测定的被动钙运动的速率常数，计算出钙泵的活性。FCAI和钙在主动和被动幽灵中的转运速率是由被包裹的偶氮砷III的吸光度计算出来的。一般来说，FCAI从1微米增加到10微米时，泵被激活。与峰值活性相比，较高的FCAI对酶活性有抑制作用。最大泵速为80微米/分钟。主要的新发现是，在给定的FCAI下，主动运输的速度似乎随着FCAI的积累速度而变化。
The activity of the Ca pump of human red blood cells was studied in resealed ghosts as a function of intracellular free Ca (fCai). Resealed ghosts were made by the agarose column method to contain, in addition to other constituents, less than 0.1 microM fCai, 100 microM arsenazo III, and either 1 mM ATP plus an ATP regenerating system (active ghosts) or no added ATP and no regenerating system (passive ghosts). The rate of Ca influx into these ghosts was manipulated by suspending them in solutions containing various combinations of free Ca (1-30 microM) and the Ca ionophore A23187 (0.1-0.7 microM). Entering Ca increased the fCai and stimulated the pump in active ghosts. In passive ghosts, all the Ca movement could be described by a single rate constant. The activity of the Ca pump was calculated from the rate of net Ca uptake in the active ghosts, using the rate constant for passive Ca movement as determined in the passive ghosts. fCai and the rates of Ca transport in both active and passive ghosts were calculated from the absorbance of entrapped arsenazo III. In general, increasing fCai from 1 to 10 microM activated the pump. Higher fCai caused an inhibition compared with peak activity. The maximum rate of pumping was 80 microM/min. The major new finding is that the rate of active transport at a given fCai appeared to vary with the rate of fCai accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)