Correlation of Adenosine Triphosphate Levels in Chara corallina with the Activity of the Electrogenic Pump

The effect of a number of inhibitors on the ATP level in single cells of Chara corallina has been measured using the luciferin-luciferase assay. The uncouplers of phosphorylation, carbonyl cyanide m-chlorophenyl hydrazone and 2,4-dinitrophenol, and the ATPase inhibitors, dicyclohexyl-carbodimide and diethylstilbestrol, all caused a marked reduction of the ATP level. These inhibitors also produced a large increase in the membrane resistance and a depolarization of the membrane potential to the diffusion potential. This is consistent with the plasmalemma containing an ATP-dependent electrogenic pump that provides the primary conductance through the membrane.