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Oxidative phosphorylation in mitochondria from livers showing cloudy swelling
Abstract:
Using succinate and alpha-ketoglutarate as substrates, oxidative phosphorylation has been measured in mitochondria isolated from livers showing cloudy swelling. This cellular change was obtained by injecting rats with S. typhi murium toxin and guinea pigs with diphtheria toxin. It has been found that phosphorylation associated with the oxidation of either of these substrates was partially inhibited in mitochondria from livers showing cloudy swelling, while the oxygen consumption was unchanged. Thus, the P:O ratios for both succinate and alpha-ketoglutarate were lower in mitochondria from treated animals than they were in normal mitochondria. Dephosphorylation of ATP was not significantly modified in mitochondria from livers showing cloudy swelling as compared with normal controls. No dephosphorylation of AMP and G-6-P was observed either in normal mitochondria or in mitochondria from treated animals.
Insights
Mitochondria from livers with cloudy swelling show inhibited oxidative phosphorylation, indicated by lower P:O ratios for succinate and alpha-ketoglutarate oxidation. Oxygen consumption remained unchanged, suggesting specific impacts on ATP synthesis.
Area of Science:
- Biochemistry
- Cellular Biology
- Toxicology
Background:
- Cloudy swelling is a cellular alteration observed in liver tissue.
- Toxins like S. typhi murium and diphtheria toxin induce liver cloudy swelling in animal models.
- Oxidative phosphorylation is a critical cellular process for ATP production in mitochondria.
Purpose of the Study:
- To investigate the effects of liver cloudy swelling on mitochondrial oxidative phosphorylation.
- To determine if cellular damage impacts ATP synthesis efficiency.
- To assess the P:O ratios using specific substrates in affected mitochondria.
Main Methods:
- Isolated mitochondria from rat and guinea pig livers exhibiting cloudy swelling induced by toxins.
- Measured oxidative phosphorylation using succinate and alpha-ketoglutarate as substrates.
- Quantified oxygen consumption and inorganic phosphate esterification (phosphorylation).
Main Results:
- Mitochondria from livers with cloudy swelling exhibited partial inhibition of phosphorylation linked to succinate and alpha-ketoglutarate oxidation.
- Oxygen consumption rates were not significantly altered in affected mitochondria.
- The P:O ratios for both substrates were reduced in mitochondria from treated animals compared to controls.
- No significant differences in ATP, AMP, or glucose-6-phosphate dephosphorylation were observed.
Conclusions:
- Liver cloudy swelling impairs mitochondrial oxidative phosphorylation efficiency, specifically affecting ATP synthesis.
- The observed reduction in P:O ratios suggests a defect in the coupling of electron transport to ATP production.
- These findings highlight the detrimental impact of toxic cellular injury on mitochondrial bioenergetics.
