Myeloperoxidase (MPO) is a heme enzyme abundantly expressed in polymorphonuclear neutrophils. MPO is enzymatically capable of catalyzing the generation of reactive oxygen species (ROS) and the consumption of nitric oxide (NO). Thus MPO has both potent microbicidal and, upon binding to the vessel wall, pro-inflammatory properties. Interestingly, MPO - a highly cationic protein - has been shown to bind to both endothelial cells and leukocyte membranes. Given the anionic surface charge of red blood cells, we investigated binding of MPO to erythrocytes. Red blood cells (RBCs) derived from patients with elevated MPO plasma levels showed significantly higher amounts of MPO by flow cytometry and ELISA than healthy controls. Heparin-induced MPO-release from patient-derived RBCs was significantly increased compared to controls. Ex vivo experiments revealed dose and time dependency for MPO-RBC binding, and immunofluorescence staining as well as confocal microscopy localized MPO-RBC interaction to the erythrocyte plasma membrane. NO-consumption by RBC-membrane fragments (erythrocyte "ghosts") increased with incrementally greater concentrations of MPO during incubation, indicating preserved catalytic MPO activity. In vivo infusion of MPO-loaded RBCs into C57BL/6J mice increased local MPO tissue concentrations in liver, spleen, lung, and heart tissue as well as within the cardiac vasculature. Further, NO-dependent relaxation of aortic rings was altered by RBC bound-MPO and systemic vascular resistance significantly increased after infusion of MPO-loaded RBCs into mice. In summary, we find that MPO binds to RBC membranes in vitro and in vivo, is transported by RBCs to remote sites in mice, and affects endothelial function as well as systemic vascular resistance. RBCs may avidly bind circulating MPO, and act as carriers of this leukocyte-derived enzyme.

• MeSH
• Acute Coronary Syndrome blood   pathology   MeSH
• Aorta drug effects   MeSH
• Biological Transport MeSH
• Endothelium, Vascular drug effects   MeSH
• Vascular Resistance drug effects   MeSH
• Erythrocytes metabolism   pathology   MeSH
• Heparin chemistry   MeSH
• Cells, Cultured MeSH
• Humans MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Organ Culture Techniques MeSH
• Nitric Oxide metabolism   pharmacology   MeSH
• Peroxidase blood   pharmacology   MeSH
• Heart drug effects   MeSH
• Heart Failure blood   pathology   MeSH
• Tissue Culture Techniques MeSH
• Protein Binding MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

We assessed blood-brain barrier (BBB) disruption in early stage of photothrombotic focal cerebral ischemia in the rat. We specifically looked for contralateral changes in BBB permeability and tested the influence of two anesthetics on the results. Adult Wistar rats were randomly anesthetized with pentobarbital (PB) or ketamine-xylazine (KX). Rats received intravenously (i.v.) Rose Bengal followed by Evans Blue (EB). Stereotactically defined spots on denuded skull were irradiated by laser (532 nm) for 18 min. Twenty four hours later, rats were killed, brains perfused, fixated, sectioned and slices analyzed by fluorescence microscopy. Volume of necrosis and volume of EB-albumin extravasation were calculated. Evidence of BBB breakdown in remote brain areas was sought and compared to sham handled controls. BBB disruption was consistently present, frequently with EB-albumin accumulating cells. Total lesion volume did not significantly differ among groups (TLVPB=9.4±1.3 mm³ vs. TLVKX=8.3±2.1 mm³); same was true for the volume of necrosis (NVPB=5.1±0.7 mm³ vs. NVKX=6.3±1.9 mm³). However, volume of EB-albumin extravasation area was significantly smaller in KX group (EBEVPB=4.3±0.8 mm³ vs. EBEVKX=2.0±0.5 mm³; p=0.0293). Median background EB-fluorescence signal density was higher in PB group (p<0.0001). Furthermore, regional increase in EB-fluorescence was found in two animals in PB group. Our study shows that anesthesia with NMDA-antagonist ketamine and α2-adrenergic agonist xylazine may reduce BBB breakdown in photothrombosis. Pentobarbital anesthesia lead to increased BBB permeability in the contralateral hemisphere.

• MeSH
• Adrenergic alpha-2 Receptor Agonists pharmacology   MeSH
• Anesthetics pharmacology   MeSH
• Excitatory Amino Acid Antagonists pharmacology   MeSH
• Blood-Brain Barrier drug effects   pathology   MeSH
• Hypnotics and Sedatives pharmacology   MeSH
• Intracranial Thrombosis pathology   MeSH
• Brain Ischemia pathology   MeSH
• Ketamine pharmacology   MeSH
• Rats MeSH
• Lasers MeSH
• Necrosis pathology   MeSH
• Pentobarbital pharmacology   MeSH
• Rats, Wistar MeSH
• Receptors, N-Methyl-D-Aspartate antagonists & inhibitors   MeSH
• Nitrogen Mustard Compounds pharmacology   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

• MeSH
• European Union MeSH
• Research MeSH
• Publication type
• Abstracts MeSH
• Geographicals
• Europe MeSH

• Conspectus
• Veřejné zdraví a hygiena
• NML Fields
• veřejné zdravotnictví
• politologie, politika, zdravotní politika

• About
• Commission of the European Communities. Biomedical and Health Research Programme Authority