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Relation between extra- and intramitochondrial ATP/ADP ratios in rat liver mitochondria
Biochimica Et Biophysica Acta
|May 9, 1980
Summary
Mitochondrial ATP/ADP ratios were measured in rat liver cells. Intramitochondrial ratios correlated with cellular respiration and pyruvate carboxylase activity, not extramitochondrial ratios, challenging the role of adenine nucleotide translocase in respiration control.
Area of Science:
- Biochemistry
- Cellular Respiration
- Mitochondrial Function
Background:
- The adenine nucleotide translocase (ANT) is crucial for mitochondrial energy metabolism.
- Its role in regulating respiration and ATP/ADP ratios is debated.
- Understanding these ratios is key to cellular energy homeostasis.
Purpose of the Study:
- To investigate the relationship between extra- and intramitochondrial ATP/ADP ratios.
- To determine how these ratios influence mitochondrial respiration and enzyme activity.
- To evaluate the hypothesis that ANT is rate-limiting for respiration.
Main Methods:
- Measurement of ATP/ADP ratios in rat liver mitochondria under varying respiratory states.
- Utilized ATPase or creatine/creatine kinase to manipulate extramitochondrial ATP/ADP.
- Employed Millipore filtration for rapid separation of mitochondrial pellets.
Main Results:
- Intramitochondrial ATP/ADP ratios mirrored extramitochondrial changes across most conditions.
- A notable exception was observed in the presence of atractylate.
- Oxygen uptake and pyruvate carboxylase activity correlated directly with intramitochondrial ATP/ADP ratios.
Conclusions:
- Mitochondrial ATP/ADP ratio, not the extramitochondrial, is closely linked to respiration and key metabolic activities.
- These findings suggest that ANT may not be the primary rate-limiting factor in mitochondrial respiration.
- The study provides critical insights into the regulation of cellular energy metabolism.