Grover A K, Frederickson M, Daniel E E
Can J Physiol Pharmacol. 1981 Nov;59(11):1180-3. doi: 10.1139/y81-182.
Addition of thallous ion (Tl+) inhibited the spontaneous mechanical activity of rat myometrium in K-free Krebs solutions with an I50 value of 30 microM. The corresponding value for I50 for similar inhibition by addition of K+ was 150 microM. Tl+ as well as K+-activated p-nitrophenylphosphatase (PNPPase) of isolated rat myometrium plasma membrane vesicles. Half maximal activation was caused by 0.47 mM Tl+ or 1.6 mM K+. Maximal enzyme activities obtained using Tl+ and K+ were comparable. The Km values for the substance p-nitrophenylphosphatase using Tl+ (1.24 mM) and K+ (1.46 mM) were also similar. Activation by either ion was inhibited by ouabain, Na+, inorganic phosphate, and vanadate (V +5). The results suggest that Tl+ can substitute for K+ for activation of the Na-K pump of rat myometrium plasma membrane.
在无钾的Krebs溶液中，铊离子（Tl +）的添加抑制了大鼠子宫肌层的自发机械活动，其半数抑制浓度（I50）值为30微摩尔。通过添加钾离子（K +）产生类似抑制作用的I50相应值为150微摩尔。铊离子以及钾离子可激活分离的大鼠子宫肌层质膜囊泡的对硝基苯磷酸酶（PNPPase）。半数最大激活由0.47毫摩尔的铊离子或1.6毫摩尔的钾离子引起。使用铊离子和钾离子获得的最大酶活性相当。使用铊离子（1.24毫摩尔）和钾离子（1.46毫摩尔）时，对硝基苯磷酸酶底物的米氏常数（Km）值也相似。哇巴因、钠离子、无机磷酸盐和钒酸盐（V +5）可抑制这两种离子的激活作用。结果表明，铊离子可以替代钾离子来激活大鼠子宫肌层质膜的钠钾泵。
