Rheological studies of the contractile force within platelet-fibrin clots: Effects of prostaglandin E 1, dibutyryl-cAMP and dibutyryl-cGMP

Abstract

Platelet-fibrin contractile force and the rate and extent of platelet-fibrin clot relaxation were measured in a Weissenberg rheogoniometer following recalcification of platelet-rich plasma (PRP). Following recalcification of PRP, there was a rapid increase in platelet-fibrin contractile force. Maximum platelet-fibrin contractile force was reduced by 40–80% in recalcified normal PRP following 50 minute pre-incubation with DBcAMP (5×10 −4 and 4×10 −3M). In the presence of PGE 1 (1.4×10 −4M), maximum platelet-fibrin contractile force was reduced by 50% in recalcified factor VIII-deficient PRP (in which less thrombin is generated). Rapid relaxation of contracted platelet-fibrin clots occurred in the presence of either PGE 1 or DBcAMP. No effect of DBcGMP was detected on platelet-fibrin interaction, contraction or relaxation in the rheogoniometer. These data on dynamic platelet-fibrin viscoelastic properties indicate that compounds which increase platelet cAMP levels inhibit platelet contractility.