Spectrophotometric Determination of Total Macromolecules for the Evaluation of Cellular Density in Cytotoxicity Tests

Abstract

Variation of cell number in treated cultures relative to the controls is an indicator of toxicity frequently employed in cytotoxicity tests. Cell density is generally determined from the amount of macromolecular components (DNA, proteins) measured by colorimetric methods. Another established procedure is the neutral red (NR) uptake test, which, in principle, permits an evaluation of the amount of viable cells in the different samples. We have devised a simple method for comparing cell density in the cultures, based on the spectrophotometric determination of the total macromolecules present in the cell monolayers solubilised in alkali after removal of the soluble fraction (TM test). When applied in parallel with the NR assay in a cell viability assay, our TM test gives a concordant rank of toxic potency for the chemicals tested. In comparison with NR uptake, the TM method appears to be more accurate and the data it provides are less prone to variation.