REDUCED THROMBOGENICITY OF TYPE-VI COLLAGEN AS COMPARED TO TYPE-I COLLAGEN

Type VI collagen has been recently identified as a major constituent o f vascular subendothelium where it serves as a binding site for von Wi llebrand factor. The present study compares the functional characteris tics of type VI collagen with those of type I collagen with respect to platelet aggregating and secretory activities. The differences betwee n the two collagens in platelet aggregation and serotonin and beta-thr omboglobulin release were found to be highly significant (p<0.001,p<0. 0007,p<0.005 respectively). Our results indicate that under in vitro c onditions, type VI collagen stimulates a significantly lesser platelet activation and aggregation response than collagen I, suggesting that type VI collagen may play a role in vivo to limit the platelet thrombo tic response following injury to the vascular subendothelium.