A-23187, also known as Calcimycin or Calcium Ionophore III, is a calcium ionophore that rapidly equilibrates intracellular and extracellular calcium concentrations. It is commonly used for <i>in situ</i> calibrations of fluorescent calcium indicators. The ionophore allows Mn² to enter the cells and quench intracellular fluorescence of calcium indicators.
<ul>
<li>White solid soluble in DMSO</li>
<li>Store at 4°C and protect from light</li>
<li>C₂₉H₃₇N₃O₆</li>
<li>MW: 523.6</li>
<li>[52665-69-7]</li>
</ul>
Also see 4-bromo A-23187. Because 4-bromo A-23187 is nonfluorescent, it is preferred over the blue fluorescent A-23187 for calibrations of UV-excited Ca² indicators such as Indo-1 and Fura-2 in order to keep background fluorescence to a minimum.