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Perfusate cytochrome c reduction in isolated rabbit lungs
R D Bongard1, D L Roerig, M R Johnston
1Department of Physiology, Medical College of Wisconsin, Milwaukee 53226.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 1, 1991
Summary
Ascorbate released from lungs significantly reduces ferricytochrome c in isolated lung perfusion systems. This reduction is primarily mediated by ascorbate, not superoxide or glutathione.
Area of Science:
- Biochemistry
- Physiology
- Respiratory System
Background:
- Ferricytochrome c reduction in isolated lung perfusion systems is a known phenomenon.
- The specific reducing agents responsible and their mechanisms remain incompletely understood.
Purpose of the Study:
- To identify the reducing agents responsible for ferricytochrome c reduction in isolated rabbit lungs.
- To differentiate between stable and short-lived reducing agents and their proximity dependence.
Main Methods:
- Isolated rabbit lungs were perfused for 1 hour in a recirculating system.
- Ferricytochrome c was added to the perfusate or to samples post-perfusion.
- Enzymatic inhibition studies using superoxide dismutase and ascorbate oxidase were performed.
Main Results:
- Recirculating cytochrome c was reduced at ~1.76 µmol/h, with 22% inhibited by superoxide dismutase.
- The majority of reduction was inhibited by ascorbate oxidase in the perfusate.
- Reduction in post-perfusion samples was almost entirely inhibitable by ascorbate oxidase.
- Reduced glutathione levels were insufficient to account for significant reduction.
Conclusions:
- Ascorbate released from the lungs is the primary contributor to ferricytochrome c reduction in this model.
- The reduction is largely mediated by stable agents like ascorbate, rather than short-lived species or proximity effects.