Histological, immunocytochemical and biochemical analyses on nature and releasing mechanism of Weibel-Palade body.

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It is well known that Weibel-Palade bodies (WP) contain von Willebrand factor and have an important role in the adhesion of blood platelets to the endothelium after vascular injuries.Since the concept as to endothelial derived relaxing factor (EDRF) and endothelial derived constricting factor (EDCF) has progressed, a role of endothelial cells in vasomotion becomes more and more notified and, therefore WP derived from Golgi complex is supposed to contain not only von Willebrand factor but also some other polypeptides.In the previous study by ours, the in vitro swine coronary artery remarkably contracts by addition of 10^<-3>M histamine. Ultrastructural alterations during the histamine-induced contraction are the increase in number and size of the intraendocellular vacuoles, the dilatation of interendothelial clefts, and the enhancement of the endothelial permeability as determined by marker experiments using horseradish peroxidase.On these grounds, we performed the following four experiments for the present project. 1. Culture of endothelial cells of the swine coronary artery in MEM containing [^<35>S] methionine at a final concentration of 100uci/ml for 16 hr and analysis of radioactive polypeptides released from the endothelial cells by 2D-PAGE. 2. Culture of the arterial segments as described above and analysis of endothelial-derived polypeptides. 3. Culture of the arterial segments as described above with an addition of 10-3m histamine. 4. Culture of the arterial segments with and without an addition of histamine releasers such as compound 48/80, calcium ionophore (A23187) and PMA.From these experiments, we analyze polypeptides (120K) released from WP during the coronary artery contraction. Whether these polypeptides are involved in the vasocontraction is under investigation.