Net adenosine triphosphate synthesis driven by an external electric field in rat liver mitochondria

Rat liver mitochondria irradiated with external electric pulses (760 V/cm, 30 ms, rectangular) catalyzed net ATP synthesis of 0.055 nmol/mg protein/pulse. The amount of ATP synthesized increased on increasing the number, voltage and duration of the electric pulses. There was no apparent threshold voltage or duration for ATP synthesis in the ranges tested (0-760 V/cm and 0.05-30 ms). The energy applied to the mitochondrial membrane within a much shorter time than the turnover time of H+-ATPase must be stored in the membrane until it is utilized for ATP synthesis. Synthesis of ATP was inhibited by the specific H+-ATPase inhibitor aurovertin and by high concentrations of uncouplers. The energy transfer inhibitors oligomycin and dicyclohexylcarbodiimide had no effect on synthesis of ATP in mitochondria by electric pulses, but inhibited oxidative phosphorylation under the same conditions. In contrast to the pulse-driven ATP synthesis in subchloroplast particles, that in intact mitochondria required hexokinase-glucose, higher ADP concentration, lower osmolarity and protection against the pH effect of the electrodes.