The major drawback of using Fluo-4 AM is that it requires an organic anion transporter inhibitor, such as probenecid, to prevent leakage. This can hinder the studies that require extended monitoring time and longer cellular retention. To address the issue, a novel Ca²⁺ indicator, Calbryte 520 AM, was developed. We compared the performance of Fluo-4 AM and Calbryte 520 AM following prolonged incubation periods after cell loading. Cells loaded with Calbryte 520 AM retained the dye for up to 24 h while exhibiting significant fluorescence brightness and superior F_max/F₀ ratios (F_max: fluorescence intensity upon stimulation; F₀: intensity before stimulation). It demonstrated that the longer retention of Calbryte 520 AM can be exploited to accommodate for the extended time required when monitoring calcium dynamics.

中文翻译：

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一种用于长期跟踪细胞内钙通量的新型 Ca2+ 指示剂。

使用 Fluo-4 AM 的主要缺点是它需要有机阴离子转运蛋白抑制剂，如丙磺舒，以防止泄漏。这可能会阻碍需要延长监测时间和更长细胞保留时间的研究。为了解决这个问题，开发了一种新型 Ca ²⁺ 指示剂 Calbryte 520 AM。我们比较了 Fluo-4 AM 和 Calbryte 520 AM 在细胞加载后延长孵育期后的性能。装载 Calbryte 520 AM 的细胞保留染料长达 24 小时，同时表现出显着的荧光亮度和优异的 F _max /F ₀比率（F _max：刺激时的荧光强度；F ₀：刺激前的强度）。结果表明，可以利用 Calbryte 520 AM 的更长保留时间来适应监测钙动态所需的延长时间。