Endothelin-1 causes P-selectin-dependent leukocyte rolling and adhesion within rat mesenteric microvessels.
Endothelin-1 (ET-1) is a potent vasoconstrictor postulated to play a role in hypertension, ischemia-reperfusion, and atherosclerosis. In addition to these contributions, it has been also proposed to induce leukocyte-endothelial cell interactions. The aim of the present study was to assess the mechanisms of action of ET-1 on leukocyte recruitment in vivo. Intravital microscopy of the rat mesenteric postcapillary venules was used. Ten minutes after 1 nM ET-1 superfusion, a significant increase in leukocyte rolling (77.5 +/- 22.6 vs. 20.5 +/- 4.5 cells/min) and adhesion (15.5 +/- 2.9 vs. 3.0 +/- 0.8 cells/100 micrometer) but not emigration was observed. These effects were found not to be mediated by mast cell activation. No platelet-endothelial cell interactions were detected in this in vivo system and furthermore, flow cytometry analysis revealed no increase of P-selectin expression in rat platelets on ET-1 stimulation. Pretreatment of animals with an anti-rat P-selectin monoclonal antibody (mAb) dramatically reduced leukocyte rolling and adhesion by 100 and 94% respectively when compared with control mAb-treated animals. At this dose of ET-1, a very transient decrease in shear rate was detected, arteriolar diameter was significantly reduced but venular diameter remained unchanged. A similar mechanical reduction in blood flow did not induce leukocyte recruitment. Thus this study demonstrates that ET-1 can directly cause significant leukocyte rolling and adhesion adding to its potential pathophysiological role in the development of disease states of the cardiovascular system.
Sanz
M J
MJ
Immunology Research Group, University of Calgary, Calgary, Alberta T2N 4N1. maris.j.sanz@uv.es
Johnston
B
B
Issekutz
A
A
Kubes
P
P
D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D019332:Endothelin-1 / Q000494:pharmacology*; D007962:Leukocytes / Q000187:drug effects* / Q000502:physiology*; D019007:P-Selectin / Q000502:physiology*; D051381:Rats; D012039:Regional Blood Flow / Q000187:drug effects; D013152:Splanchnic Circulation / Q000502:physiology*; D013314:Stress, Mechanical; D014699:Venules / Q000187:drug effects / Q000502:physiology
D019332:Endothelin-1; D019007:P-Selectin