TY - JOUR
T1 - Tumor necrosis factor-α-induced leukocyte adhesion and microvessel permeability
AU - Zeng, Min
AU - Zhang, Hong
AU - Lowell, Clifford
AU - He, Pingnian
PY - 2002/12/1
Y1 - 2002/12/1
N2 - The objective of this study was to investigate whether leukocyte adhesion and/or emigration are critical steps in increased microvessel permeability during acute inflammation. To conduct this study, we combined autologous blood perfusion with a single microvessel perfusion technique, which allows microvessel permeability to be measured precisely after the endothelium has interacted with blood-borne stimuli. Experiments were carried out in intact venular microvessels in rat mesenteries. Firm attachment of leukocytes to endothelial cells was induced by intravenous injection of TNF-α (3.5 μg/kg) and resuming autoperfusion in a precannulated microvessel. Leukocyte emigration was facilitated by superfusion of formyl-Met-Leu-Phe-OH. Microvessel permeability was measured as hydraulic conductivity (Lp) or the solute permeability coefficient to tetramethylrhodamine isothiocyanate-labeled α-lactalbumin before and after leukocyte adhesion and emigration in individually perfused microvessels. We found that perfusion of a microvessel with TNF-α did not affect basal microvessel permeability, but intravenous injection of TNF-α caused significant leukocyte adhesion. However, the significant leukocyte adhesion and emigration did not cause corresponding increases in either Lp or solute permeability. Thus our results suggest that leukocyte adhesion and emigration do not necessarily increase microvessel permeability and the mechanisms that regulate the adhesion process act independently from mechanisms that regulate permeability. In addition, silver staining of endothelial boundaries demonstrated that leukocytes preferentially adhere at the junctions of endothelial cells. The appearance of the silver lines indicates that the TNF-α-induced firm adhesion of leukocyte to microvessel walls did not involve apparent changes in the junctional structure of endothelial cells, which is consistent with the results of permeability measurements.
AB - The objective of this study was to investigate whether leukocyte adhesion and/or emigration are critical steps in increased microvessel permeability during acute inflammation. To conduct this study, we combined autologous blood perfusion with a single microvessel perfusion technique, which allows microvessel permeability to be measured precisely after the endothelium has interacted with blood-borne stimuli. Experiments were carried out in intact venular microvessels in rat mesenteries. Firm attachment of leukocytes to endothelial cells was induced by intravenous injection of TNF-α (3.5 μg/kg) and resuming autoperfusion in a precannulated microvessel. Leukocyte emigration was facilitated by superfusion of formyl-Met-Leu-Phe-OH. Microvessel permeability was measured as hydraulic conductivity (Lp) or the solute permeability coefficient to tetramethylrhodamine isothiocyanate-labeled α-lactalbumin before and after leukocyte adhesion and emigration in individually perfused microvessels. We found that perfusion of a microvessel with TNF-α did not affect basal microvessel permeability, but intravenous injection of TNF-α caused significant leukocyte adhesion. However, the significant leukocyte adhesion and emigration did not cause corresponding increases in either Lp or solute permeability. Thus our results suggest that leukocyte adhesion and emigration do not necessarily increase microvessel permeability and the mechanisms that regulate the adhesion process act independently from mechanisms that regulate permeability. In addition, silver staining of endothelial boundaries demonstrated that leukocytes preferentially adhere at the junctions of endothelial cells. The appearance of the silver lines indicates that the TNF-α-induced firm adhesion of leukocyte to microvessel walls did not involve apparent changes in the junctional structure of endothelial cells, which is consistent with the results of permeability measurements.
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U2 - 10.1152/ajpheart.00787.2001
DO - 10.1152/ajpheart.00787.2001
M3 - Article
C2 - 12388263
AN - SCOPUS:0036889890
SN - 0363-6135
VL - 283
SP - H2420-H2430
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 6 52-6
ER -