CyQUANT™ LDH Cytotoxicity Assay (Invitrogen™)

The CyQUANT LDH Cytotoxicity Assay is a colorimetric assay that provides a simple and reliable method for determining cellular cytotoxicity. Lactate dehydrogenase (LDH) is a cytosolic enzyme present in many different cell types that is released into the cell culture medium upon damage to the plasma membrane. The CyQUANT LDH Cytotoxicity Assay provides the reagents to accurately and quantitatively measure this extracellular LDH.

Note: The CyQUANT LDH Cytotoxicity Assay (Cat. Nos. C20300 and C20301) are direct replacements for the Pierce LDH Cytotoxicity Assay Kit (Cat. Nos. 88953 and 88954).

CyQUANT LDH Cytotoxicity Assay features include:
• Convenient—add-mix-read assay format for adherent and suspension cells, including 3D cell models
• Accurate—provides a quantitative measurement of LDH release
• Flexible—ideal for high-throughput screening, monitor cytotoxicity from the same sample over time
• Robust—uses stable LDH enzyme activity as a cytotoxic marker

LDH is a cytosolic enzyme present in many different cell types and is a well-established and reliable indicator of cellular toxicity. Damage of the plasma membrane results in a release of LDH into the surrounding cell culture medium. This extracellular LDH can be quantified by a coupled enzymatic reaction in which LDH catalyzes the conversion of lactate to pyruvate via NAD+ reduction to NADH. Diaphorase then uses NADH to reduce a tetrazolium salt (INT) to a red formazan product that can be measured at 490 nm. The level of formazan formation is directly proportional to the amount of LDH released into the medium.

The CyQUANT LDH Cytotoxicity Assay provides the reagents needed for the simple, reliable colorimetric quantification of cellular cytotoxicity. The kit can be used with different cell types, including 3D cell models, to measure cytotoxicity mediated by chemical compounds as well as cell-mediated cytotoxicity. Since LDH in the medium is the indicator of cellular cytotoxicity, the assay can be used to monitor cytotoxicity from the same sample over time. To perform the assay, an aliquot of the cell culture medium is transferred to a new plate and the reaction mixture is added. After a 30-minute incubation, the reaction is stopped by adding Stop Solution and absorbance is measured using a microplate reader.