Depleted level of heparan sulfate proteoglycan in the extracellular matrix of endothelial cell cultures exposed to endotoxin.

Exposure of cultured endothelial cells to endotoxin causes an increase in the amount of cellular heparan sulfate proteoglycan and a depletion of this molecule in the extracellular matrix. Concomitant with the decrease in the extracellular matrix is the appearance of a fraction of proteoglycan bearing altered carbohydrate moieties in the culture medium. beta-mercaptoethanol, mannitol, and dimethyl sulfoxide bring back to normal the structural properties of the proteoglycan in the medium and restore the matrix content in proteoglycan to a level comparable to that of control cells but do not affect the increase in the amount of proteoglycan on the cell. This "uncoupling" suggests that two independent chains of events underlie the synthetic and structural changes of the proteoglycan triggered by endotoxin in the endothelial cell.