Substrate analyses in single cells: I. Determination of ATP

Subfemtomole quantities of ATP were determined using luminescence analysis with firefly extracts. The methodological advances include development of microtechniques for sample handling, and recording of the time profile of the light emission by photon counting in connection with multichannel techniques. The amount of ATP in isolated single cells of the microorganisms Paramecium, Peridinium, and of macrophages from the abdominal cavity of mice were assayed. These cells represented a range from 0.07 to 2.5 ng dry mass as assessed with automatic interferometric scanning.