A simple and sensitive method for monitoring drug-induced cell injury in cultured cells

A simple, sensitive method has been developed for evaluating cell injury noninvasively in monolayer cells in culture. The cell ATP pool was radiolabeled by incubating the cells with [14C]adenine. The uptake and incorporation of [14C]adenine was shown to proportional to the number of cells. As determined by HPLC, about 65-70% of the incorporated 14C label was in the ATP pool, 15-20% was in the ADP pool, and the rest was in the 5'-AMP pool. When prelabeled cells were exposed to toxic drugs (acetaminophen, calcium ionophore A-23187, or daunomycin) there was a marked decrease in cell ATP with a concomitant increase in leakage of labeled nucleotides, mainly 5'-AMP and 5'IMP. We have shown that leakage of 14C label into the medium from the prelabeled cells may be employed for quantitation of cell injury. This new measure of toxicity was shown to correlate very well with LDH leakage from the cells, which is a well accepted measure of cell injury. The leakage of 5'-[14C]AMP also correlated very well with the reduction of cell ATP in cardiac myocytes. This method has been used for monitoring drug-induced toxicity in liver cells, cardiac myocytes, and LB cells.