Phytosterol-stimulated production of plasminogen activator in endothelial cells from bovine carotid artery

Abstract

The endothelial cell is a rich source of plasminogen activator that is associated with fibrinolytic activity in blood vessel. Addition of fucosterol or sitosterol to the culture medium of endothelial cells from bovine carotid artery gave rise to a marked increment in the intracellular and extracellular activities of plasminogen activator. Removal of fucosterol or sitosterol from the culture medium resulted in a decrease of plasminogen activator activity back to normal levels. No enhancement of plasminogen activator activity in cultured endothelial cells was observed by cholesterol, 5-androsten-3β-ol and other steroids and sex hormones including androsterone, testosterone, estrone and estradiol. Synthesis of plasminogen activator in cells induced with fucosterol or sitosterol was inhibited by protein synthesis inhibitor, cycloheximide. The plasminogen activators produced in cells were classified into urokinase-type activators with molecular weights of 31, 000 and 55, 000 and tissue-type ones with molecular weights of 81, 000 and 130, 000, which were identified with respective antibodies. The synthesis of each type of plasminogen activator in endothelial cells was stimulated by fucosterol or by sitosterol.