摘要:

ABSTRACTSources of reactive O2species in the vessel wall that potentially contribute to the control of vascular tone include NADPH oxidases, arachidonic acid metabolizing enzymes, xanthine oxidase, nitric oxide synthase and mitochondria. Specific physiological stimuli (such as changes in PO2) as well as pathophysiological stimuli control the production of reactive O2species by many of these sources. Certain key reactive O2species activate specific signalling mechanisms that control vascular tone, often through processes involving the metabolism of these species. The production of prostaglandins and cyclic GMP are some of the most sensitive systems regulated by hydrogen peroxide; whereas the conversion of nitric oxide (NO) to peroxynitrite (ONOO−) and inhibition of the stimulation of the cytosolic form of guanylate cyclase are processes that are very sensitive to superoxide anion (O2·−). High levels of NO production readily result in the formation of significant amounts of ONOO−, because NO competes with superoxide dismutase for the metabolism of cellular O2·−and thereby activates additional signalling mechanisms such as regulation through thiol nitrosation. As the levels of individual reactive O2species increase, other signalling mechanisms likely to participate in vascular responses to oxidant injury seem to become activated. Thus, evidence is developing to support the concept that reactive O2species are important contributors to the control of vasc

ISSN:1073-9688    

DOI:10.3109/10739689609146778

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACTObjective:To obtain cultures of rodent brain microvascular endothelium (BMEC) that retain endothelial cell‐specific markers and functions for two purposes: investigating whether these cultures contain endothelial cell‐specific storage granules or Weibel‐Palade bodies and have the ability to rapidly bind neutrophils upon cytokine induction; and setting the groundwork for future studies examining endothelium derived from mice strains with targeted deficiencies in endothelial adhesion molecules.Methods:Capillaries were obtained by collagenase/dispase digestion and subsequent density centrifugation of either rodent brain or meninges. The yield was then plated onto fibronectin‐coated dishes. For some studies, pure murine endothelial cultures were obtained by flow‐cytometric sorting, using uptake of fluorescently labeled diI‐acetylated low‐density lipoprotein as a marker for endothelium. Endothelial cell‐specific markers were analyzed via immunofluorescence, immunoprecipitation and light microscopy. Cytokine‐induced neutrophil adhesion and associated upregulation of leukocyte adhesion molecules were measured as described previously for human umbilical vein endothelial cells.Results:BMEC possess numerous von Willebrand factor–containing Weibel‐Palade bodies and synthesize and secrete all multimeric forms of von Willebrand factor. They take up diI‐acetylated low‐density lipoproteins, contain platelet‐endothelial cell adhesion molecules and form capillary‐like structures on three‐dimensional extracellular matrix substrates. Sorted murine brain microvascular endothelial cells treated with IL‐1β or TNF‐α for 4 h show an increase in surface expression of the cytokine‐inducible leukocyte adhesion molecules E‐selectin, VCAM‐1, and ICAM‐1, and they support rapid neutrophil adhesion, which is, on average, three times greater than that of nonstimulated cells.Conclusions:The brain microvascular endothelial cultures described here exhibit many of the markers of endothelial cells including the presence of Weibel‐Palade bodies. The localization of von Willebrand factor almost exclusively to Weibel‐Palade bodies indicates that murine cerebral endothelium has evolved an efficient mechanism for storage of this platelet adhesion protein, which plays an important role in hemostasis. In addition, this is the first demonstration of rapid neutrophil adhesion to murine brain microvascular endothelial cells. Finally, the reproducible culture and the characterization of murine BMEC makes feasible future studie

ISSN:1073-9688    

DOI:10.3109/10739689609146779

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACTObjective:The selectins are a family of adhesion molecules that mediate leukocyte rolling, a prerequisite for their later firm adhesion and migration to sites of inflammation. The N‐terminal lectin domain of selectins is important for Ca2+‐dependent binding to oligosaccharide ligands. We set out to study the effect of peptides corresponding to residues 11–20, 23–30, 36–50, 54–63, 70–79 and 109–118 (counting from the N‐terminus of the mature proteins) of the lectin domain of human L‐, P‐ and E‐selectins on leukocyte rollingin vivo.Methods:Peptides were applied by local intravascular microinfusion via a glass micropipette into rat mesenteric venules. Visibly rolling cells were counted off‐line and compared with rolling cells counted during control periods.Results:Peptides corresponding to residues 70–79 of P‐selectin and 11–20 of L‐selectin reduced leukocyte rolling flux in rat mesenteric venules to less than 30% of that measured during control infusion. Peptides corresponding to residues 109–118 of P‐selectin, 54–63 of L‐selectin and 23–30 of E‐selectin also reduced leukocyte rolling flux, although to a lesser degree.Conclusions:We have shown that small peptides based on the lectin domain of all three selectins can be eff

ISSN:1073-9688    

DOI:10.3109/10739689609146780

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACTObjective:Oxidative stress from increased production of reactive oxygen species or decreased efficiency of inhibitory and scavenger systems may contribute to vascular injury. In this study, we developed anin vitromodel of vascular injury by menadione‐induced oxidative stress in bovine heart microvascular endothelial cells.Methods:Oxidative stress was induced by exposure to menadione. Superoxide, hydrogen peroxide and hydroxyl radical formation was measured by superoxide dismutase‐inhibitable cytochrome c reduction, the dichlorofluorescin technique and the salicylate method, respectively. Electron paramagnetic‐spin resonance spectroscopy employing 5–5′‐dimethyl‐1‐pyrroline‐N‐oxide for superoxide trapping was used. Endothelial cell cytotoxicity was assessed by lactate dehydrogenase release.Results:Superoxide and hydroxyl radical were produced in a time‐ and concentration‐dependent fashion. Fluorescence in the presence of dichlorofluorescin confirmed hydrogen peroxide formation. Endothelial cell cytotoxicity became evident after 5 h of menadione treatment at concentrations of 100 μM. 3‐Aminobenzamide, a poly(ADP‐ribose)polymerase inhibitor, and dimethylthiourea, a hydrogen peroxide and hydroxyl radical scavenger, decreased menadione cytotoxicity, whereas deferoxamine, an inhibitor of hydroxyl radical formation, did not.Conclusions:The results suggest that menadione toxicity is mediated by poly(ADP‐ribose)polymerase activation via hydrogen peroxide formation and that menadione‐treated bovine heart microvessel endothelial cells provide a suitablein vitromodel to study oxida

ISSN:1073-9688    

DOI:10.3109/10739689609146781

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACTObjective:The deformation of erythrocytes in microvessels less than 15 μm in inner diameter was analyzed using a microvascular bed isolated from rabbit mesentery. The deformation was compared with that found in glass capillaries.Methods:Human erythrocytes were perfused through two media: first, a microvascular‐bed section isolated from rabbit mesentery; and second, a set of glass capillaries. Images of deformed erythrocytes were recorded on videotape under strobe light and analyzed with an image processor. The flow velocity of the erythrocytes was determined from the difference of their positions between video frames or by a dual‐spot cross‐correlation technique. Erythrocyte deformability was modified with diamide, diazene dicarboxylic acid bis[N,N‐dimethylamide], by crosslinking spectrins.Results:Symmetrical (parachute‐like or slipper‐like) deformation of erythrocytes was observed only in microvessels smaller than 13 μm in inner diameter. Erythrocytes in microvessels were less deformed than those in glass capillaries with corresponding diameters, and the marginal cell‐free layer was narrower. The deformation increased by increasing the flow velocity of erythrocytes, and the cell‐free layer became wider. Diamide‐treated cells in microvessels were less deformed than normal cells and showed slightly narrower cell‐free layers. Stronger stress in narrower microvessels induced further deformation of cells.Conclusions:Erythrocyte deformation in microvessels was essentially different from that in glass capillaries, and the effect of erythrocyte deformability on the flow dynamics of erythrocytes in microvessels was properly evaluated using an isola

ISSN:1073-9688    

DOI:10.3109/10739689609146782

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACTObjective:To measure the magnitude of the water‐exclusive pathway in cat skeletal muscle.Methods:The osmotic reflection coefficient (σd) was measured for sucrose, raffinose and cyancobalamine using osmotic transient techniques in the isolated, perfused cat hindlimb preparation at sufficiently high perfusate flows (60–80 ml/min−1100 g−1) so that solute diffusion was not a factor. Microvascular filtration coefficient values required for the σddetermination were measured using the capillary filtration coefficient (CFC) technique at these high flows. With these σddata and macromolecular reflection coefficient data from a previous study, discrete pore‐modeling techniques were used to estimate the magnitude of the water movement through the water‐exclusive pathway.Results:CFC values increased significantly at very high flows (>80 ml/min−1100 g−1), but these values were unchanged from control at the lower flows used to measure σd. The σdvalues for sucrose and raffinose were 0.41 ± 0.03 SE and 0.42 ± 0.03 SE, respectively, in 12 limbs. In the same limbs, the σdfor cyancobalamine was 0.52 ± 0.03 SE, which was significantly (p<0.05) larger, consistent with a larger Stokes‐Einstein radius for this molecule. A 3‐pathway model (small and large pores and a water‐exclusive pathway) was fit to the data. The result was that 41 ± 4% (95% confidence interval) of total water flow makes use of the water‐exclusive pathway in this preparation.Conclusions:The very high fraction of water flow through the water‐exclusive pathway in cat skeletal muscle suggests that this pathway is of major importance in microvascular water movement under normal conditions. Failure to take this finding into account can lead to inaccuracies in the estimation of paramet

ISSN:1073-9688    

DOI:10.3109/10739689609146783

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:1073-9688    

DOI:10.3109/10739689609146784

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:1073-9688    

DOI:10.3109/10739689609146785

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY