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The effect of pyrrolnitrin on mitochondrial reactions: the induction of swelling
Abstract:
An antifungal antibiotic, pyrrolnitrin, was found to show very similar biological activities to those of imidazole antimycotics on isolated mitochondria. Pyrrolnitrin caused drastic swelling of mitochondria in isotonic solutions of alkali metal salts and of sucrose without any addition of substrate for the respiratory chain in mitochondria. The swelling induced by pyrrolnitrin was characterized by a biphasic swelling process; a very fast initial swelling and thereafter a very slow speed secondary swelling. The increase of pyrrolnitrin concentration exponentially increased the magnitude of over-all rapid swelling. Pyrrolnitrin enhance the latent ATPase activity of mitochondria at the similar range of concentrations to those needed for the induction of the swelling. The concentrations of pyrrolnitrin where mitochondrial swelling was induced were found to be far lower than those needed for the exhibition of inhibitory effect on the electron transport system of mitochondria.
Insights
Pyrrolnitrin, an antifungal antibiotic, causes rapid mitochondrial swelling and enhances ATPase activity, similar to imidazole antimycotics. These effects occur at lower concentrations than those inhibiting mitochondrial electron transport.
Area of Science:
- Biochemistry
- Mitochondrial Physiology
- Antifungal Drug Action
Background:
- Pyrrolnitrin is an antifungal antibiotic with known biological activities.
- Imidazole antimycotics represent a class of antifungal agents with established mechanisms of action.
- Isolated mitochondria serve as a model system for studying cellular energy metabolism and drug effects.
Purpose of the Study:
- To investigate the biological activities of pyrrolnitrin on isolated mitochondria.
- To compare the effects of pyrrolnitrin with those of imidazole antimycotics.
- To elucidate the mechanism of pyrrolnitrin-induced mitochondrial dysfunction.
Main Methods:
- Isolated mitochondria were treated with pyrrolnitrin in isotonic solutions.
- Mitochondrial swelling was monitored in the presence of alkali metal salts and sucrose.
- ATPase activity and electron transport system inhibition were assessed at varying pyrrolnitrin concentrations.
Main Results:
- Pyrrolnitrin induced biphasic mitochondrial swelling, characterized by rapid initial and slow secondary phases.
- The magnitude of swelling increased exponentially with pyrrolnitrin concentration.
- Pyrrolnitrin enhanced latent mitochondrial ATPase activity at concentrations lower than those inhibiting electron transport.
Conclusions:
- Pyrrolnitrin exhibits biological activities on isolated mitochondria similar to imidazole antimycotics.
- Mitochondrial swelling and ATPase enhancement are key effects of pyrrolnitrin, occurring at sub-inhibitory concentrations for electron transport.
- Pyrrolnitrin's mechanism of action may involve disruption of mitochondrial membrane integrity and energy metabolism.