ACUTE TOXICITY MEASUREMENTS ON AQUATIC POLLUTANTS USING MICROCALORIMETRY ON TISSUE-CULTURED CELLS

A new microcalorimetric bioassay for acute cellular toxicity is based on metabolic heat evolution from tissue-cultured human cells. The assay is quantitative, inexpensive, and versatile; moreover, toxicological information can be obtained with cells from other species of interest. The biological response to toxicants is inhibition of heat production in cells and toxicity is expressed as the concentration 50% effective in this inhibition (EC50). The system can therefore measure acute toxicity for a broad range of toxicants having target sites in various cellular metabolic pathways. Average heat production in HeLa cells is 40 pW/cell and the reproducibility is 5 pW/cell. Cell samples range from 8 x 10(5) to 2 x 10(6) cells and yield signals of 30-80-mu-W in the absence of toxicants. These signals are readily measurable in an LKB Model 10700-1 flow microcalorimeter. Results are compared with those obtained with the Beckman Microtox bioassay and the Escherichia coli electrode and with rainbow trout 96-h LC50 values.