abstract |
A bioassay method is based on the detection of changes in the membrane potential of individual cells. A cell suspension is incubated with a solution of a substance capable of affecting the physiology of at least a subpopulation of cells in the suspension. During or after the incubation, a measurement representative of the membrane potential of individual cells is made. The preferred method of measuring membrane potential involves incubating the cells with a membrane-permeant, fluorescent, ionic dye which becomes distributed on opposite sides of the cell membrane as a function of membrane potential, and then assaying intracellular dye concentration by photometric measurements in a flow cytometer. n<??>In one embodiment the cells are modified prior to the photometric measurements; this modification may involve reaction with, for example, hormones, pharmacological agents and proteins. n<??>One application of the invention is in the evaluation of drugs. |