title: Reactive oxygen metabolites inhibit spontaneous lymphatic contractions.
abstract: The effects of oxygen-derived free radicals on the contractile activity of the mesenteric collecting lymphatics were evaluated in the anesthetized rat. Lymphatic contractions were monitored before, during and after the application of oxyradicals. Contraction frequency (F), stroke volume (SV), ejection fraction (EF), contraction propagation (PC), and lymph pump flow (LPF) were determined from the lymphatic diameter tracings. Oxyradicals were generated using hypoxanthine and xanthine oxidase. Exposure to oxyradicals inhibited the lymphatic pumping mechanism: 1) F fell from 15.5 +/- 0.8 to 0.8 +/- 0.7 beats/min; 2) EF went from 0.44 +/- 0.02 to 0.08 +/- 0.04; 3) PC dropped from 92 +/- 2 to 56 +/- 8%; and 4) LPF fell precipitously from 41.0 +/- 5.2 to 0.7 +/- 0.4 nl/min. The effects of the oxyradicals were attenuated by superoxide dismutase, implicating superoxide anion as one of the predominant causative agents. We conclude that oxyradicals significantly inhibit the lymph pump and that this inhibition could be a factor contributing to the formation of interstitial edema during inflammation.
authors.affiliation: Microcirculation Research Institute, College of Medicine, Texas A&M University, College Station 77843-1114.
authors.forename: D C
authors.initials: DC
authors.lastname: Zawieja
authors.forename: S T
authors.initials: ST
authors.lastname: Greiner
authors.forename: K L
authors.initials: KL
authors.lastname: Davis
authors.forename: W M
authors.initials: WM
authors.lastname: Hinds
authors.forename: H J
authors.initials: HJ
authors.lastname: Granger
mesh_terms: D000818:Animals; D005609:Free Radicals; D019271:Hypoxanthine; D007042:Hypoxanthines / Q000494:pharmacology; D008208:Lymphatic System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D010100:Oxygen / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013318:Stroke Volume; D013482:Superoxide Dismutase / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*; D014969:Xanthine Oxidase / Q000494:pharmacology
chemical_list: D005609:Free Radicals; D007042:Hypoxanthines; D019271:Hypoxanthine; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D010100:Oxygen