Inhibition and enhancement of platelet aggregation by collagen derivatives.

Rat tail tendon tropocollagen rapidly caused the aggregation of blood platelets coincident with collagen multimerization. Several long-chain alkyl derivatives of collagen, however, were completely unable to induce platelet aggregation even at unusually high concentrations. These collagen derivatives varied in their polymerization properties , and the polymerization of tropocollagen derivatives was shown not necessarily to be a prerequisite for platelet aggregation. These collagen derivatives may enhance the antithrombogenic properties of collagenbased prosthese. A short-chain derivative, collagen-glycine ethyl ester, profoundly enhanced platelet aggregation in the absence of any measurable polymerization. This derivative may be useful as a growth-promoting burn dressing.