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Rat heart mitochondria release adenosine
Abstract:
Isolated rat heart mitochondria release adenosine under specific conditions. Lowest adenosine release occurs at 4 degrees C while highest release occurs in the presence of pyruvate + malate or rotenone at 30 degrees C. The release is attenuated during state 3 respiration, in the presence of atractyloside or in the presence of 1799. Oligomycin only partially decreases adenosine release. Release is unaffected by 200 microM Ca++ and is independent of oxygen concentration as low as 2 microM. The data are consistent with the hypothesis that adenosine is released from mitochondria via the adenine nucleotide transporter and the release is regulated by the intramitochondrial ATP to ADP ratio.
Insights
Isolated rat heart mitochondria release adenosine, particularly when pyruvate + malate or rotenone are present at 30°C. This release is linked to the adenine nucleotide transporter and regulated by the mitochondrial ATP/ADP ratio.
Area of Science:
- Mitochondrial Physiology
- Biochemistry
- Cellular Respiration
Background:
- Mitochondria are crucial for cellular energy production.
- Adenosine release from mitochondria is not fully understood.
- Mitochondrial adenine nucleotide transporter (ANT) plays a key role in nucleotide exchange.
Purpose of the Study:
- To investigate the conditions and mechanisms of adenosine release from isolated rat heart mitochondria.
- To determine the relationship between mitochondrial respiration and adenosine release.
- To test the hypothesis that adenosine release is mediated by the ANT and regulated by the intramitochondrial ATP/ADP ratio.
Main Methods:
- Isolated rat heart mitochondria were used.
- Adenosine release was measured under various conditions including different temperatures (4°C vs. 30°C).
- The effects of respiratory substrates (pyruvate + malate), inhibitors (rotenone, oligomycin), atractyloside, 1799, calcium (Ca++), and oxygen concentration were assessed.
Main Results:
- Adenosine release was temperature-dependent, with higher release at 30°C compared to 4°C.
- Pyruvate + malate or rotenone significantly increased adenosine release at 30°C.
- State 3 respiration, atractyloside, and 1799 attenuated adenosine release, while oligomycin had a partial effect.
- Adenosine release was independent of Ca++ (200 microM) and low oxygen concentrations (down to 2 microM).
Conclusions:
- Mitochondrial adenosine release is facilitated by the adenine nucleotide transporter.
- The release is modulated by the intramitochondrial ATP to ADP ratio.
- Specific conditions, including the presence of certain substrates and inhibitors, influence adenosine efflux from mitochondria.