核苷酸对钙通量的影响。

The influence of nucleotides on calcium fluxes.

作者信息

Dipolo R

出版信息

Fed Proc. 1976 Dec;35(14):2579-82.

Abstract

The effect of ATP and other nucleotides on calcium efflux was studied in squid axons dialyzed with Ca:ethylene glycol tetraacetic acid buffers to control the internal ionized calcium concentration. In the virtual absence of internal ATP (ca. 1 muM) a significant level of calcium efflux occurs which could be increased by the addition of internal ATP. At low concentrations of ionized calcium (ca. 200 nM), efflux increased 10-fold. At high levels of ionized calcium (ca. 100 muM), the increase was only twofold. This stimulation of efflux by ATP requires internal sodium. Conversely, ATP renders the calcium efflux insensitive to internal sodium and prevents the inhibition of calcium efflux produced by internal sodium in the absence of ATP. Of 12 nucleotides tested, only ATP, deoxy-ATP and alpha, beta-methylene ATP significantly stimulated calcium efflux. The data are interpreted as indicating that ATP induces an affinity in change in the carrier system binding calcium to the internal site, possibly by a phosphorylating step.

摘要

在用钙

乙二醇四乙酸缓冲液透析以控制内部游离钙浓度的乌贼轴突中，研究了ATP和其他核苷酸对钙外流的影响。在几乎没有内部ATP（约1μM）的情况下，会发生显著水平的钙外流，添加内部ATP可使其增加。在低浓度游离钙（约200 nM）时，外流增加了10倍。在高浓度游离钙（约100μM）时，增加仅两倍。ATP对外流的这种刺激需要内部钠离子。相反，ATP使钙外流对内部钠离子不敏感，并防止在没有ATP的情况下内部钠离子对钙外流的抑制。在所测试的12种核苷酸中，只有ATP、脱氧ATP和α，β-亚甲基ATP能显著刺激钙外流。这些数据被解释为表明ATP可能通过磷酸化步骤诱导载体系统中与内部位点结合的钙的亲和力发生变化。