[Adherence of monocytes to the aortic endothelium. Effect of the intraluminal pressure].

It is now generally accepted that most of the foam cells formed in the early fatty streak arise from circulating monocyte-macrophages. The effect of transmural pressure on mononuclear cells adherence to the vascular endothelium has been studied in excised rabbit thoracic aorta. Mononuclear cells were obtained from blood by centrifugation through lymphocyte separation medium (Ficoll-Paque, specific gravity 1.077). The mononuclear cell layer was collected from the interface and washed twice in RPMI containing 10 p. 100 fetal calf serum to remove contaminating platelets. The mononuclear cells were radiolabeled by incubation for 60 min in 0.1 mCi/ml of 51-chromium. After incubation, the cells were washed twice to remove free chromium, and resuspended in 5 ml RPMI containing 10 p. 100 fetal calf serum, at a concentration of 2 x 10(6) cells/ml. After ligature of intercostal arteries, 2 segments from the descending thoracic aorta were excised at in vivo length and under physiological pressure in order to preserve endothelial integrity. Arterial segments were incubated in oxygenated Krebs solution, at 39 degrees C and the intraluminal solution was changed to the solution containing the labeled mononuclear cells. The pressure was established at 70 mmHg in one segment and at 160 mmHg in the other. After 2 h incubation, the vessels were fixed under pressure. Each arterial segment was opened longitudinally and cut into 4 segments, which were laid on a microscopic slide and frozen at -20 degrees C. The surface area of each segment was measured and sections were cut en face at 20 micron intervals from the luminal surface to the adventitia.(ABSTRACT TRUNCATED AT 250 WORDS)