Abstract
Various assays are in use to determine the effect of a drug on cells propagated in vitro. The trypan blue exclusion test is a rapid method to assess cell viability in response to environmental insults. When membrane integrity of the cells is compromised, there is uptake of the dye into the cells so that viable cells, which are unstained, appear clear with a refractile ring around them and nonviable cells appear dark blue colored with no refractile ring around them. Sulforhodamine B Assay (SRB) is based on the binding of the dye to basic amino acids of cellular proteins, and colorimetric evaluation provides an estimate of total protein mass, which is related to cell number. This assay has been widely used for the in vitro measurement of cellular protein content of both adherent and suspension cultures. AlamarBlue is used to monitor the reducing environment of proliferating cells. Because it is non-toxic, cells exposed to it can be returned to culture or used for other purposes. AlamarBlue takes advantage of mitochondrial reductase to convert nonfluorescent resazurin to fluorescent resorufin.