Ray T K
Can J Physiol Pharmacol. 1980 Oct;58(10):1189-91. doi: 10.1139/y80-181.
Ba2+ at low concentrations (1 mM or lower) stimulates the basal and K+-stimulated para-nitrophenyl phosphatase activity associated with the purified microsomal fractions from the oxyntic cells of bullfrog gastric mucosa. However, at higher concentrations Ba2+ acts as a competitive inhibitor of the K+-stimulated phosphatase. Ba2+ alone, in absence of any Mg2+, cannot maintain the enzyme activity; hence Ba2+ can only influence or modulate the Mg2+-dependent phosphatase. The effects are unique for Ba2+ because all other divalent cations such as Ca2+ and Zn2+ act as inhibitors of this enzyme under similar conditions. The data offer a possible biochemical basis for the known pharmacological effects of Ba2+ in gastric acid secretion.
低浓度（1 mM或更低）的Ba2+可刺激与牛蛙胃黏膜壁细胞纯化微粒体组分相关的基础和K+刺激的对硝基苯磷酸酶活性。然而，在较高浓度下，Ba2+作为K+刺激的磷酸酶的竞争性抑制剂。在没有任何Mg2+的情况下，单独的Ba2+不能维持酶活性；因此，Ba2+只能影响或调节依赖Mg2+的磷酸酶。这些作用对Ba2+来说是独特的，因为在类似条件下，所有其他二价阳离子如Ca2+和Zn2+都作为该酶的抑制剂。这些数据为Ba2+在胃酸分泌中的已知药理作用提供了一个可能的生化基础。
