Ultrasensitive assay for ribonucleoside triphosphates in 50-1000 cells. Application to studies with pyrazofurin and mycophenolic acid.

New methods have been developed for the measurement of ATP, GTP, and UTP pools of microscopic cell colonies of 50-1000 cells. These methods are based on stoichiometric generation of ATP from ADP with GTP and UTP serving as phosphate donors, followed by measurement of ATP with firefly luciferase. This technique has been used to generate dose-response curves describing the effects of mycophenolic acid and pyrazofurin on individual colonies of Chinese hamster ovary cells.