Evaluation of arginine-glycine-aspartate-containing peptides as inhibitors of equine platelet function.

The research article discusses an experiment conducted in horses to assess whether synthetic peptides, specifically those that contain the arginine-glycine-aspartate (RGD) sequence, can inhibit platelet function. The study found that these peptides, indeed, inhibited equine platelet aggregation and adhesion—an observation that suggests a potential use of these peptides in the treatment of thrombotic diseases in horses.

Research Objective

The aim of this study was to determine whether synthetic peptides containing the arginine-glycine-aspartate (RGD) sequence have an inhibitory effect on equine platelet function. Two peptides—a simple RGD-containing peptide (RGDS) and a more complex one (RPR 110885)—were tested both in vitro and in vivo.

Methods

• Blood samples for in vitro studies were obtained from three healthy Thoroughbreds, while in vivo and ex vivo evaluations involved four young adult pony mares.
• The synthetic peptides were added to the blood samples and the responses were compared to those involving aspirin—a known platelet function inhibitor.
• The platelet aggregation responses were determined by a turbidimetric method, a technique measuring cloudiness of a solution, and platelet adhesion to collagen was evaluated by the Baumgartner perfusion method.
• The RPR 110885 was administered intravenously at dosages of 30 and 60 micrograms/kg of body weight. The bleeding time, platelet aggregation responses, and platelet count were then determined at hourly intervals for 4 hours.

Results

• Both RGDS and RPR 110885 significantly inhibited platelet aggregation and adhesion in a dose-dependent manner.
• The concentration of RGDS required to inhibit 50% of platelet function was 100-142 microM; for RPR 110885, only 0.03–0.05 microM was needed.
• When RPR 110885 was administered to ponies in doses as low as 30 or 60 g/kg, it almost entirely halted ADP-induced platelet aggregation.

Conclusions

• The study showed that both RGDS and RPR 110885 inhibit equine platelet function. However, RPR 110885 has a potency several thousand times greater than RGDS.
• Synthetic peptides containing the RGD sequence may have potential use in the treatment of thrombotic disorders in horses.