title: Activated leukocytes and endothelial cells enhance retention of ultrasound contrast microspheres containing perfluoropropane in inflamed venules.
abstract: OBJECTIVE
  To characterize the flow dynamics of albumin ultrasound contrast microspheres containing perfluoropropane (PFP) in normal and inflamed microvasculature.
  
  
  METHODS
  Mesenteric microvessels of rats were examined after an intravenous injection of fluorocein-labeled erythrocytes or PFP microspheres by fluorescence intravital microscopy with and without local application of 10(-8) M platelet activating factor (PAF) as an experimental form of inflammation.
  
  
  RESULTS
  All the microspheres passed freely through arterioles and capillaries. Mean velocities of the microspheres in each vessel were closely correlated with those of erythrocytes. Only a minor fraction of the microspheres was retained in the venules (> or =0.1 s stoppage) by attachment to endothelial cells. The frequency of microsphere retention in venules was significantly enhanced by PAF (2.6+/-2.1%, P<0.01 vs. control), especially in regions with leukocyte adhesion. Treatment with a monoclonal antibody to intercellular adhesion molecule-1, P-selectin or the common leukocyte antigen inhibited PAF-induced microsphere retention in venules (P<0.05). In the inflamed microcirculation, a small subgroup of microspheres becomes attached to venular endothelial cells in regions with leukocyte adhesion via interaction among microspheres, activated leukocytes and endothelial cells via adhesion molecules.
  
  
  CONCLUSIONS
  In inflamed microcirculation, a small subgroup of microspheres becomes attached to venular endothelial cells in regions with leukocyte adhesion via interaction among microspheres, activated leukocytes and endothelial cells via adhesion molecules. These results suggest that ultrasonography with microspheres has the potential to evaluate inflammatory site distribution as well as tissue perfusion.
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA 92093-0412, USA. tyasu@omiya.jichi.ac.jp
authors.forename: Takanori
authors.initials: T
authors.lastname: Yasu
authors.forename: Yigal
authors.initials: Y
authors.lastname: Greener
authors.forename: Edward
authors.initials: E
authors.lastname: Jablonski
authors.forename: Anne L
authors.initials: AL
authors.lastname: Killam
authors.forename: Shunichi
authors.initials: S
authors.lastname: Fukuda
authors.forename: Makoto
authors.initials: M
authors.lastname: Suematsu
authors.forename: Shinichiro J
authors.initials: SJ
authors.lastname: Tojo
authors.forename: Geert W
authors.initials: GW
authors.lastname: Schmid-Schönbein
mesh_terms: D000818:Animals; D001794:Blood Pressure; D042783:Endothelial Cells / Q000502:physiology*; D004912:Erythrocytes; D005466:Fluorocarbons; D006339:Heart Rate; D007249:Inflammation / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007700:Kinetics; D007962:Leukocytes / Q000502:physiology*; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008863:Microspheres; D010972:Platelet Activating Factor; D051381:Rats; D017208:Rats, Wistar; D014463:Ultrasonography; D014699:Venules / Q000166:cytology / Q000473:pathology*
chemical_list: D005466:Fluorocarbons; D010972:Platelet Activating Factor; C042852:perflutren