COLLAGEN-INDUCED PLATELET SHAPE CHANGE - ROLE OF COLLAGEN QUATERNARY STRUCTURE

  • 1 January 1980
    • journal article
    • research article
    • Vol. 95  (1) , 90-98
Abstract
Multimerization of collagen molecules appears to be a prerequisite for collagen-induced [human] platelet aggregation and release. Whether a similar requirement exists for collagen-initiated platelet disc-to-sphere transformation, one of the earliest events in the platelet:collagen interaction is unknown. Platelet shape change was studied by highly purified type I collagen in the presence of EDTA to prevent interference from platelet aggregation and release. The ability of soluble collagen to induce platelet shape change was dependent on prior fibril formation. Tropocollagen from which multimers were removed was not able to initiate the disc-to-sphere transformation, indicating that monomeric collagen was insufficient as a platelet activator. Increasing the extent of multimerization by preincubation at 37.degree. C led to an increase in response rate and a decrease in lag time for initiation of shape change, but even after maximal multimerization lag time was not eliminated. Increase in turbidity of the collagen solution preceded its ability to stimulate pltelet shape change, suggesting that a minimum size of the multimer was needed for platelet activation. L-Arginine, an inhibitor of multimerization, prevented collagen-induced shape change in a dose-dependent relationship. Enhancement of the shape change response rate as a function of the concentration of collagen multimers was found.