The ATP content of disks of storage tissue of red beet is reduced under N(2) atmosphere to between 10 and 25% of its value in air. Plasmalemma fluxes of K(+) and Cl(-) are inhibited within 1 minute or less following removal of O(2), and the extent of this inhibition is entirely attributable to the depletion of ATP. The ATP content remains approximately constant or decreases slightly for up to 1 hour under N(2). On return to air, the ATP content recovers, reaching 75% of the aerobic level within 45 second.