* Neutral Red uptake: Neutral Red is a dye that accumulates in lysosomes due to their acidic pH. Lysosomes are membrane-bound organelles that contain hydrolytic enzymes, maintaining an acidic environment for their proper function.
* Dye Accumulation: Healthy cells maintain an acidic environment within their lysosomes, allowing for the uptake and accumulation of Neutral Red dye.
* Loss of Viability: When cells are damaged or dying, their lysosomes lose their ability to maintain an acidic pH. This leads to decreased uptake and accumulation of Neutral Red dye.
* Measurement: The amount of dye accumulated in the cells is measured using a spectrophotometer. A decrease in dye uptake indicates a loss of cellular viability, suggesting cell damage or death.
In contrast to the MTT assay:
* MTT Assay: Measures mitochondrial function by assessing the reduction of the yellow tetrazolium salt MTT to a purple formazan product by mitochondrial enzymes. This assay relies on the integrity and activity of mitochondria.
* Neutral Red Assay: Focuses on lysosomal function and pH maintenance. It does not directly assess mitochondrial function.
Therefore, while the MTT assay relies on the mitochondrion, the Neutral Red assay relies on the lysosome.
