Bers Donald M, Patton Chris W, Nuccitelli Richard
Department of Pharmacology, University of California, Davis School of Medicine, Davis, California, USA.
Methods Cell Biol. 2010;99:1-26. doi: 10.1016/B978-0-12-374841-6.00001-3.
Calcium (Ca(2+)) is a critical regulator of an immense array of biological processes, and the intracellular [Ca(2+)] that regulates these processes is ~ 10,000 lower than the extracellular [Ca(2+)]. To study and understand these myriad Ca(2+)-dependent functions requires control and measurement of [Ca(2+)] in the nano- to micromolar range (where contaminating Ca(2+) is a significant problem). As with pH, it is often essential to use Ca(2+) buffers to control free [Ca(2+)] at the desired biologically relevant concentrations. Fortunately, there are numerous available Ca(2+) buffers with different affinities that make this practical. However, there are numerous caveats with respect to making these solutions appropriately with known Ca(2+) buffers. These include pH dependence, selectivity for Ca(2+) (e.g., vs. Mg(2+)), ionic strength and temperature dependence, and complex multiple equilibria that occur in physiologically relevant solutions. Here we discuss some basic principles of Ca(2+) buffering with respect to some of these caveats and provide practical tools (including freely downloadable computer programs) to help in the making and calibration of Ca(2+)-buffered solutions for a wide array of biological applications.
钙（Ca(2+)）是众多生物过程的关键调节因子，而调节这些过程的细胞内[Ca(2+)]比细胞外[Ca(2+)]低约10,000倍。要研究和理解这些众多依赖钙的功能，需要控制和测量纳摩尔至微摩尔范围内的[Ca(2+)]（其中污染的Ca(2+)是一个重大问题）。与pH值一样，使用钙缓冲剂将游离[Ca(2+)]控制在所需的生物学相关浓度通常至关重要。幸运的是，有许多具有不同亲和力的可用钙缓冲剂，这使得这一操作具有可行性。然而，使用已知的钙缓冲剂适当地配制这些溶液存在许多注意事项。这些包括pH依赖性、对Ca(2+)的选择性（例如，与Mg(2+)相比）、离子强度和温度依赖性，以及在生理相关溶液中发生的复杂多重平衡。在这里，我们讨论一些关于这些注意事项的钙缓冲基本原理，并提供实用工具（包括可免费下载的计算机程序），以帮助配制和校准用于广泛生物应用的钙缓冲溶液。
