THROMBIN DECREASES GLYCOSAMINOGLYCANS CONTENT OF ENDOTHELIAL-CELLS IN CULTURE

The effect of thrombin on the metabolism of glycosaminoglycans (GAG) in cultured bovine aortic endothelial cells was investigated. Incubation of confluent endothelial cell cultures with thrombin at 1.0 NIH U/ml for 8 h and above caused a significant decrease in the accumulation of [S-35]sulfate-labeled GAG (S-35-GAG) in the cell layer. After a 24 h incubation, thrombin at 0.5 U/ml and above decreased the accumulation of S-35-GAG in both cell layer and medium. The percentage of S-35-GAG released into the medium during the last 3 h of 24 h incubation was significantly increased by thrombin. In thrombin- treated cell layer, both heparan sulfate and the other GAG was significantly decreased at the same degree. The incorporation of both [H-3]thymidine and [C-14]leucine was significantly increased by thrombin. Gabexate mesilate, a serine protease inhibitor, suppressed the thrombin inhibition. From these results, it was suggested that thrombin decreased S-35-GAG in the endothelial cell layer without a nonspecific damage of the cells through mainly an inhibition of GAG production and additionally a stimulation of GAG release.