Tissue ATP concentrations in slices of red beet increase progressively with time for up to 7 days after cutting the root. ATP levels are higher in slices taken from stored roots than in slices from fresh roots. ATP is reduced during incubation in salt solutions.Plasmalemma influxes were measured by 6 minutes incubation with (42)K and/or (36)C1 under conditions in which cation and anion influxes are independent. Both fluxes showed an approximately linear correlation with ATP level when the latter was varied by addition of CN(-), carbonyl cyanide m-chlorophenylhydrazone, or oligomycin, except for Cl influx with oligomycin, where oligomycin had a greater effect on Cl influx than could be accounted for by the reduction in ATP alone.These results support the view that K(+) and Cl(-) influxes are both energized directly or indirectly by ATP, and in addition that the Cl pump may be directly inhibited by oligomycin.