Pisareva L N, Skul'skiĭ I A, Krestinskaia T V
Tsitologiia. 1989 Feb;31(2):234-7.
Effects of sodium, lithium and amiloride on the ATPase reaction and on its potassium-dependent step were studied using membrane preparations of Na,K-ATPase. It was established that the addition of 70 mM NaCl or LiCl to the reaction medium diminished the hydrolysis of para-nitrophenyl phosphate (pNPP) by 70 and 40%, respectively. Amiloride (0.8 mM) inhibited activities of Na,K-ATPase and pNPPase by 50 and 15%, respectively. The higher concentrations of amiloride produced a more prominent inhibition of Na,K-ATPase, but not of pNPPase. There was no correlation between the effect of amiloride on the pNPP hydrolysis and potassium concentration in the medium. There was the additivity in the inhibition of pNPPase by 0.8 mM amiloride and sodium or lithium ions up to the concentrations of ions as high as 30 mM. A conclusion is made that the inhibition of Na,K-ATPase by amiloride is mediated through the modification of the sensitivity of the enzyme to sodium.
利用钠钾-ATP酶的膜制剂，研究了钠、锂和氨氯吡咪对ATP酶反应及其钾依赖性步骤的影响。结果表明，向反应介质中添加70 mM氯化钠或氯化锂分别使对硝基苯磷酸酯（pNPP）的水解减少70%和40%。氨氯吡咪（0.8 mM）分别使钠钾-ATP酶和对硝基苯磷酸酶（pNPPase）的活性抑制50%和15%。更高浓度的氨氯吡咪对钠钾-ATP酶产生更显著的抑制作用，但对对硝基苯磷酸酶没有影响。氨氯吡咪对pNPP水解的影响与介质中的钾浓度之间没有相关性。0.8 mM氨氯吡咪与钠或锂离子对对硝基苯磷酸酶的抑制作用在离子浓度高达30 mM时具有加和性。得出的结论是，氨氯吡咪对钠钾-ATP酶的抑制作用是通过改变酶对钠的敏感性介导的。
