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Reactive oxygen metabolites inhibit spontaneous lymphatic contractions
D C Zawieja1, S T Greiner, K L Davis
1Microcirculation Research Institute, College of Medicine, Texas A&M University, College Station 77843-1114.
The American Journal of Physiology
|June 1, 1991
Summary
Oxygen-derived free radicals significantly impair lymphatic pumping function in rats. This inhibition by oxyradicals suggests a role in the development of interstitial edema during inflammation.
Area of Science:
- Physiology
- Pathophysiology
- Biochemistry
Background:
- Mesenteric collecting lymphatics are crucial for fluid balance.
- Oxygen-derived free radicals (oxyradicals) are implicated in various inflammatory processes.
- The specific impact of oxyradicals on lymphatic contractile function remains incompletely understood.
Purpose of the Study:
- To investigate the effects of oxyradicals on the contractile activity of mesenteric collecting lymphatics.
- To quantify the impact of oxyradicals on key lymphatic pumping parameters.
- To identify the specific oxyradical species involved.
Main Methods:
- Anesthetized rat model used to evaluate lymphatic contractions.
- Oxyradicals generated in situ using hypoxanthine and xanthine oxidase.
- Parameters measured included contraction frequency, stroke volume, ejection fraction, contraction propagation, and lymph pump flow.
Main Results:
- Exposure to oxyradicals markedly inhibited lymphatic pumping.
- Significant reductions observed in contraction frequency (15.5 to 0.8 beats/min), ejection fraction (0.44 to 0.08), contraction propagation (92% to 56%), and lymph pump flow (41.0 to 0.7 nl/min).
- Superoxide dismutase administration attenuated these effects, indicating superoxide anion's primary role.
Conclusions:
- Oxyradicals significantly inhibit the lymphatic pump mechanism.
- This inhibition by oxyradicals may contribute to interstitial edema formation during inflammation.
- Superoxide anion is a key mediator of oxyradical-induced lymphatic dysfunction.