Cell viability tetrazolium reduction

Among the first cell viability assays developed for HTS was the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] tetrazolium reduction assay (Mosmann 1983) that served as a milestone for this type of study. The assay offered a non-radioactive alternative to tritiated thymidine incorporation into DNA as a method of measuring cell proliferation. In many cases, the MTT assay can directly substitute for the tritiated thymidine incorporation assay (Figure 6.3). The MTT tetrazolium compound is prepared in a physiologically balanced solution, added to cells in culture, and incubated for approximately 4 hr. Viable cells convert MTT into an intensely colored formazan product that can be quantitated by recording changes in absorbance at specific wavelengths. 

Measures tetrazolium salt reduction to gauge cell viability... 

The cell viability was evaluated by measuring mitochondrial dehydrogenize activity with MTT assay. This assay measures the cell activity, proliferation rate and cell viability. The yellow tetrazolium MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) is reduced to insoluble purple formazan granules by all living, metabolically active cells. The precipitated formazan was dissolved in isopropanol, and the absorbance was read at 595 nm. Absorbance values that are lower than the control cells indicate a reduction in the cell activity and viability. Conversely, a higher absorbance rate indicates an increase in cell viability/ proliferation. 

A variety of mammalian cells have been successfully cultured onto porous silicon surfaces. The first publications on this topic by Bayliss et al. demonstrated that attachment of Chinese hamster ovary (CHO) cells proceeded on porous silicon surfaces to a similar extent as on bulk silicon (Bayliss et al. 1997a, b). This was also confirmed with the neuronal cell line B50 (Bayliss et al. 2000). Cell viability in these studies was determined using two colorimetric assays, the MTT based on enzymatic reduction of a tetrazolium salt to a purple formazan and the neutral red uptake assay. B50 and CHO cells were cultured on bulk silicon, porous silicon, glass, and polycrystalline silicon. Both viability assays suggested that the neuronal cells showed preference for porous silicon above the other surfaces, while CHO cells showed the lowest viability on the porous silicon surface (Bayliss et al. 1999, 2000). The surfaces of the porous silicon used in these early studies were not modified post-etching, and it was not until a study utilized porous silicon surfaces with an oxide layer for cell culture that surface chemistry was found to play a crucial factor (Chin et al. 2001). Rat... 

Cell viability Mitocbondrial enzymes activity MTT (3-(4,5-dimethylthiazol-2-yl) Tetrazolium reduction into formazan in metabolically active cells Optometric density... 

Corrosive materials are identified by their ability to produce a deaease in cell viability below defined threshold levels at specified exposure periods, as determined using the MTT dye [3-(4,5-dimethyldiazol-2-yl)-2,5 diphenyl tetrazolium bromid] reduction assay. Skin models such as EPISKIN (NIH, 2002) and EpiDerm (ECVAM, 2001) are used. 

A variety of in vitro assays have been developed that minimize or avoid live animal experimentation. Several capitalize on the sodium channel s affinity for these toxins. Neuronal cell lines lyse in the presence of veratridine, a sodium channel activator, and ouabain, which prevents removal of the excessive sodium ions allowed in by veratridine. In the presence of both these drugs, a sodium channel blocker such as saxitoxin rescues the cells. Cellular viability can then be measured by adding tetrazolium salts that are metabolized by living cells to a colored product. Alternatively, isolated cellular membranes, typically from brain tissue, are used to bind radiolabeled saxitoxin. After incubating receptor and radioligand in the presence of a test sample, any radiolabeled saxitoxin bound to the cell membranes are deposited onto filters by vacuum pressure. Radioactivity from the labeled saxitoxin is then measured with a signal reduction indicating the presence of saxitoxin. 

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