AMI5 (Eosin Y Disodium) is a soluble acidic red dye molecule. It is commonly used as a photoredox catalyst in organic synthesis.

Right atria or sinus nodal cells are homogenized in lysis buffer consisting of (50 mM Tris-HCl pH 7.5, 100 mM KCl, 1 mM ethylenediamine tetraacetic acid, 1 mM ethylene glycol tetraacetic acid, 1 mM dithiothreitol, 0.1 mM phenylmethylsulfonyl fluoride, 0.5 mM Benzamidine, 20 mg/L Leupeptin, 20 mM sodium pyrophosphate, 50 mM NaF, and 50 mM sodium β-glycerophosphate), and total protein content is determined by the Bradford assay. Caspase-3 activity is determined by EnzChek Caspase-3 Assay Kit[3].