Thiol-oxidant monochloramine mobilizes intracellular Ca2+ in parietal cells of rabbit gastric glands.
Thiol-oxidant monochloramine mobilizes intracellular Ca2+ in parietal cells of rabbit gastric glands.
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DOI：
10.1152/ajpcell.00189.2006
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发表时间：
2007-11
期刊：
影响因子：
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通讯作者：
Breda M. Walsh;H. Naik;J. Matthew Dubach;Melissa Beshire;Aaron M. Wieland;D. Soybel
中科院分区：
文献类型：
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作者：
Breda M. Walsh;H. Naik;J. Matthew Dubach;Melissa Beshire;Aaron M. Wieland;D. Soybel
在幽门螺杆菌诱导的胃炎中，氧化剂是通过管腔内的细菌、激活的粒细胞和胃粘膜细胞的相互作用而产生的。在这项研究中，我们探索了一类这样的氧化剂，以一氯胺(NH(2)Cl)为代表，作为胃腺壁细胞内钙积累的激动剂的能力。从兔胃粘膜分离出单个胃腺，分别在胞浆内(Fura-2AM)或细胞内储存物(MAG-Fura-2AM)内标记Ca(2+)。调整条件以筛选出这些记者具有亲和力的金属阳离子(如锌(2+))的贡献。暴露于NH(2)Cl(高达200微米)导致细胞内钙离子浓度([Ca(2+)](I))呈剂量依赖性增加，高于基线水平200-400 nM。这些改变可以用氧化剂清除剂维生素C或硫醇还原剂二硫苏糖醇(DTT)来预防，DTT可以保护细胞内的硫醇基团免受氯化氧化剂的氧化。在持续暴露于NH(2)Cl的过程中引入维生素C可阻止但不能逆转胞浆中Ca(2+)的积累。相反，DTT或N-乙酰半胱氨酸的引入可以阻止和部分逆转NH(2)Cl的作用。NH(2)Cl诱导胞质内Ca(2+)的积累是由于胞内贮藏物释放、胞外液进入和胞外排出障碍所致。处理Ca(2+)的蛋白质容易被氯胺氧化，导致[Ca(2+)](I)持续增加。在某些条件下，NH(2)Cl可能不是刺激物，而是激活细胞内信号通路的试剂。抗NH(2)Cl策略应考虑氧化剂、清除剂和硫醇还原剂的不同作用。
In Helicobacter pylori-induced gastritis, oxidants are generated through the interactions of bacteria in the lumen, activated granulocytes, and cells of the gastric mucosa. In this study we explored the ability of one such class of oxidants, represented by monochloramine (NH(2)Cl), to serve as agonists of Ca(2+) accumulation within the parietal cell of the gastric gland. Individual gastric glands isolated from rabbit mucosa were loaded with fluorescent reporters for Ca(2+) in the cytoplasm (fura-2 AM) or intracellular stores (mag-fura-2 AM). Conditions were adjusted to screen out contributions from metal cations such as Zn(2+), for which these reporters have affinity. Exposure to NH(2)Cl (up to 200 microM) led to dose-dependent increases in intracellular Ca(2+) concentration ([Ca(2+)](i)), in the range of 200-400 nM above baseline levels. These alterations were prevented by pretreatment with the oxidant scavenger vitamin C or a thiol-reducing agent, dithiothreitol (DTT), which shields intracellular thiol groups from oxidation by chlorinated oxidants. Introduction of vitamin C during ongoing exposure to NH(2)Cl arrested but did not reverse accumulation of Ca(2+) in the cytoplasm. In contrast, introduction of DTT or N-acetylcysteine permitted arrest and partial reversal of the effects of NH(2)Cl. Accumulation of Ca(2+) in the cytoplasm induced by NH(2)Cl is due to release from intracellular stores, entry from the extracellular fluid, and impaired extrusion. Ca(2+)-handling proteins are susceptible to oxidation by chloramines, leading to sustained increases in [Ca(2+)](i). Under certain conditions, NH(2)Cl may act not as an irritant but as an agent that activates intracellular signaling pathways. Anti-NH(2)Cl strategies should take into account different effects of oxidant scavengers and thiol-reducing agents.