ATP synthesis is coupled to rat liver mitochondrial RNA synthesis

Rat liver mitochondria respond to changes in energy demand by modulating th e amount of RNA synthesized. Coupled rat liver mitochondria were used to de termine the relationship between mitochondrial respiration, ATP levels, and mitochondrial transcription. This system included oxidizable substrates (m alate and glutamate) and constituents that could support both mitochondrial respiration and transcription. The respiratory inhibitor rotenone, phospho rylation inhibitor oligomycin, and the uncoupler of oxidative phosphorylati on carbonyl-cyanide p-triflouromethoxyphehylhydrazone inhibited RNA synthes is. Addition of ADP stimulated mitochondrial transcription and peak RNA syn thesis was observed at 1-2 mM ADP. At ADP concentrations above 2 mM, RNA sy nthesis decreased. These results demonstrate that mitochondrial transcripti on is tightly coupled to ATP levels.