Activation and damage of endothelial cells upon hypoxia/reoxygenation. Effect of extracellular pH.

Disturbances of blood flow upon vascular occlusions and spasms result in hypoxia and acidosis, while its subsequent restoration leads to reoxygenation and pH normalization (re-alkalization) in ischemic sites of the vascular bed. The effect of hypoxia/reoxygenation on activation and stimulation of apoptosis in cultured human endothelial cells was studied. The cells were subjected to hypoxia (2% O2, 5% CO2, 93% N(2)) for 24 h followed by reoxygenation (21% O2, 5% CO2, 74% N(2)) for 5 h.

Production of soluble P-selectin by platelets and endothelial cells.

The distribution of a soluble form of a cell adhesion molecule, P-selectin, in human platelets and cultivated endothelial cells has been studied by enzyme-linked immunosorbent assay (ELISA). The concentration of soluble P-selectin in the blood plasma of healthy donors and patients with abnormal platelet count has also been determined. P-selectin was measured in the Triton X-100 lysate of platelets and endothelial cells (total P-selectin), in the 100,000g supernatant obtained after sedimentation of the membrane fraction from the homogenate of sonicated platelets and endothelial cells (intracellular soluble P-selectin), in the supernatant of activated and nonactivated platelets, and in the culture medium of endothelial cells.

[Interaction of platelets with 125I-labelled collagen type III. The necessity for forming a fibrillary structure].

The interaction of type III collagen (CIII) with washed human platelets was studied, using a CIII preparation from human placenta. CIII was labeled with 125I, and the monomeric and fibrillar forms of 125I-CIII (125I-CIIIm and 125I-CIIIf, respectively) were incubated with the platelets at room temperature. The platelet-associated and free labels were separated by centrifugation through 20% sucrose.