Summary

Regulated secretion provides a means by which endothelial cells(EC) can rapidly and selectively alter the microenvironment of individualvascular beds, and modulate the interrelated processes of coagulation,fibrinolysis, and inflammation. The rapid release of high molecularweight multimers of von Willebrand factor (VWF) and surfaceexpression of P-selectin in response to a wide variety of stimuli havebeen well documented, and are the result of exocytosis of Weibel-Palade bodies (WPB). The regulated release of other EC secretory proteins,including tissue plasminogen activator (tPA), interleukin-8,endothelin-1, and multimerin, has also been described. New light isbeing shed on how secretory proteins are selectively targeted to storagegranules in EC, and on the molecular and cellular events that compriseregulated secretion. Knowledge of the mechanisms of sorting andsecretion from EC storage granules may provide basis for new strategiesfor treating inflammatory and coagulation disorders.