title: Role of oxygen radicals in the microcirculatory manifestations of postischemic injury.
abstract: Reperfusion after transient tissue ischemia constitutes an irrevocable need to preserve tissue viability. However, release of prolonged ischemia will either result in failure of the microcirculation to reperfusion (no-reflow) and thus the prolongation of hypoxia, or in restoration of blood flow resulting in reoxygenation of the inflicted tissue. While ischemia damages the tissue primarily through hypoxia-induced depletion of energy stores, reoxygenation paradoxically contributes to tissue damage through the formation of oxygen radicals, the release of chemoattractant mediators (TNF, IL-1, LTB4), and the activation of circulating polymorphonuclear leukocytes (PMNs). Through the action of chemoattractant mediators and the upregulation of leukocytic (CD11/CD18) and endothelial adhesion receptors (ICAM, GMP-140), activated PMNs adhere to the endothelium, release further chemoattractants and oxygen radicals and undertain a vicious circle, which will ultimately result in further tissue damage. Both the no-reflow phenomenon and the events initiated by reflow--termed herein as the reflow-paradox--contribute to the failure of the nutritive microvascular perfusion and loss of tissue viability following ischemia and reperfusion.
authors.affiliation: Institut für Chirurgische Forschung, Klinikum Grosshadern, Ludwig-Maximilians-Universität München.
authors.forename: M D
authors.initials: MD
authors.lastname: Menger
authors.forename: H A
authors.initials: HA
authors.lastname: Lehr
authors.forename: K
authors.initials: K
authors.lastname: Messmer
mesh_terms: D000818:Animals; D004730:Endothelium, Vascular / Q000503:physiopathology; D005609:Free Radicals; D006801:Humans; D007511:Ischemia / Q000503:physiopathology*; D015227:Lipid Peroxidation / Q000502:physiology*; D008833:Microcirculation / Q000503:physiopathology*; D009504:Neutrophils / Q000502:physiology; D010100:Oxygen / Q000502:physiology*; D015427:Reperfusion Injury / Q000503:physiopathology*; D013481:Superoxides / Q000378:metabolism
chemical_list: D005609:Free Radicals; D013481:Superoxides; D010100:Oxygen