Calculation of the pentose phosphate and Embden-Myerhoff pathways from a single incubation with [U-14C]- and [5-3H]glucose.

A method that simultaneously determines Embden-Myerhoff pathway and pentose phosphate pathway (PPP) activities from an incubation with [U-14C]- and [5-3H]glucose is presented. The method relies on the use of unlabeled pyruvate and lactate to dilute out radiolabel entering the tricarboxylic acid cycle. Gluconeogenesis from pyruvate is prevented by the use of an incubation chamber that maintains a CO2 (and bicarbonate) free environment. The method, which includes the contribution by the recycling steps of the PPP, is especially useful when biological material is limited or developmental timing is critical.