Fluorescent Ca²⁺ indicators have been essential for the analysis of Ca²⁺ signaling events in various cell types. We showed that chemical Ca²⁺ indicators, but not a genetically encoded Ca²⁺ indicator, potently suppressed the activity of Na⁺- and K⁺-dependent adenosine triphosphatase (Na,K-ATPase), independently of their Ca²⁺ chelating activity. Loading of commonly used Ca²⁺ indicators, including Fluo-4 acetoxymethyl (AM), Rhod-2 AM, and Fura-2 AM, and of the Ca²⁺ chelator BAPTA AM into cultured mouse or human neurons, astrocytes, cardiomyocytes, or kidney proximal tubule epithelial cells suppressed Na,K-ATPase activity by 30 to 80%. Ca²⁺ indicators also suppressed the agonist-induced activation of the Na,K-ATPase, altered metabolic status, and caused a dose-dependent loss of cell viability. Loading of Ca²⁺ indicators into mice, which is carried out for two-photon imaging, markedly altered brain extracellular concentrations of K⁺ and ATP. These results suggest that a critical review of data obtained with chemical Ca²⁺ indicators may be necessary.

荧光Ca ²⁺指示剂对于分析各种细胞类型中的Ca ²⁺信号传递事件至关重要。我们表明化学Ca ²⁺指标，而不是遗传编码的Ca ²⁺指标，有效地抑制了Na ⁺ -和K ⁺依赖性腺苷三磷酸酶（Na，K-ATPase）的活性，而与它们的Ca ²⁺螯合活性无关。装载常用的Ca ²⁺指示剂，包括Fluo-4乙酰氧基甲基（AM），Rhod-2 AM和Fura-2 AM，以及Ca ²⁺将螯合剂BAPTA AM掺入培养的小鼠或人类神经元，星形胶质细胞，心肌细胞或肾脏近端小管上皮细胞中可将Na，K-ATPase活性抑制30％至80％。Ca ²⁺指示剂还抑制了激动剂诱导的Na，K-ATPase活化，改变了代谢状态，并引起了细胞活力的剂量依赖性丧失。为进行双光子成像而将Ca ²⁺指示剂加载到小鼠体内，可显着改变大脑中K ⁺和ATP的浓度。这些结果表明，可能需要对使用化学Ca ²⁺指标获得的数据进行严格的审查。