Activated leukocytes and endothelial cells enhance retention of ultrasound contrast microspheres containing perfluoropropane in inflamed venules.
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.
Yasu
Takanori
T
Department of Bioengineering, University of California San Diego, La Jolla, CA 92093-0412, USA. tyasu@omiya.jichi.ac.jp
Greener
Yigal
Y
Jablonski
Edward
E
Killam
Anne L
AL
Fukuda
Shunichi
S
Suematsu
Makoto
M
Tojo
Shinichiro J
SJ
Schmid-Schönbein
Geert W
GW
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*
D005466:Fluorocarbons; D010972:Platelet Activating Factor; C042852:perflutren