用注射的三磷酸鸟苷刺激预先暴露于醛固酮的藤壶肌纤维中的钠外流。

Stimulation by injected guanosine triphosphate of the sodium efflux in barnacle muscle fibres pre-exposed to aldosterone.

Bittar E E, Nwoga J

J Physiol. 1981;313:499-511. doi: 10.1113/jphysiol.1981.sp013678.

Abstract

A study has been made of the response of the Na efflux to injected guanosine triphosphate (GTP) in barnacle muscle fibres pre-exposed to aldosterone. 2. (i) Injection of GTP into unpoisoned fibres causes a transitory stimulation. By contrast, injection of GTP into ouabain-poisoned fibres causes a sustained stimulation. Little or no fall in Em is recorded following GTP injection. (ii) The stimulatory response to GTP of aldosterone pre-exposed ouabain-poisoned fibres differs from that seen in unexposed, ouabain-poisoned fibres, in that its magnitude is greater and always sustained. 3. The magnitude of the response to GTP depends on external Ca and pH but not external Na. The response itself is not seen at 0 degrees C. 4. (i) Verapamil reduces the size of the response to GTP only if applied before GTP. Injection of EGTA, Fe, Zn and Co partially abolishes the residual response. (ii) Injection of MgCl2 almost completely reverses the response to GTP. KCl is ineffective. 5. These results are explained by supposing that removal of internal Mg and trace elements by GTP leads to activation of phosphoprotein phosphatase.

摘要

对预先暴露于醛固酮的藤壶肌纤维中，注射三磷酸鸟苷（GTP）后钠外流的反应进行了一项研究。2. （i）向未中毒的纤维中注射GTP会引起短暂的刺激。相比之下，向哇巴因中毒的纤维中注射GTP会引起持续的刺激。注射GTP后记录到的Em几乎没有下降或没有下降。（ii）预先暴露于醛固酮的哇巴因中毒纤维对GTP的刺激反应与未暴露的哇巴因中毒纤维不同，其幅度更大且总是持续的。3. 对GTP的反应幅度取决于外部钙和pH值，但不取决于外部钠。在0摄氏度时看不到这种反应本身。4. （i）维拉帕米仅在GTP之前应用时才会减小对GTP的反应大小。注射乙二醇双四乙酸（EGTA）、铁、锌和钴会部分消除残余反应。（ii）注射氯化镁几乎完全逆转对GTP的反应。氯化钾无效。5. 假设GTP去除内部镁和微量元素会导致磷蛋白磷酸酶激活，这些结果就得到了解释。