Heparan sulfate as a venostatic endothelial stabilizing factor.

A humoral transfer of a factor inducing a decrease of circulating endothelial cells (CEC) released during venostasis was demonstrated in rats. The possibility to block its activity by an in-vitro addition of protamine suggests its identity with an endogenous heparan sulfate possessing an inhibitory effect on endothelial turnover. This was supported by an analogous effect of intravenously administered heparan sulfate-related agent.