LDH Cytotoxicity Assay

Lactate dehydrogenase (LDH) is a soluble cytosolic enzyme present in most eukaryotic cells. LDH releases into culture medium upon cell death due to damage of plasma membrane. The increase of the LDH activity in culture supernatant is proportional to the number of lysed cells. LDH Cytotoxicity Assay kit provides a colorimetric method to measure LDH activity using a reaction cocktail containing lactate, NAD+, Diaphorase and INT. LDH catalyzes the reduction of NAD+ to NADH in the presence of L-lactate, while the formation of NADH can be measured in a coupled reaction in which the tetrazolium salt INT is reduced to a red formazan product. The amount of the highly colored and soluble formazan can be measured at 490 nm spectrophotometrically.