Inhibition of Platelet Aggregation by Putrescine, Spermidine, and Spermine in Hypercholesterolemic Rabbits

Background holesterolemia causes alterations in platelet function. Platelet hyperaggregation is considered a predisposing factor for atherosclerosis. In this paper, the antiaggregating effect of the polyamines putrescine, spermidine, and spermine was studied on platelets of normal and hypercholesterolemic rabbits. s aland rabbits were fed with a cholesterol-enriched diet for 10 weeks. Lipids and glucose were determined in serum. The assays of platelet aggregation were carried out using platelet-rich plasma (PRP) obtained from both control and cholesterol-fed rabbits. We used 2.5 μmol /mL ADP and 2 μg/mL collagen as inductors of platelet aggregation. In addition, arginase activity and L-arginine content were determined in PRP. s total cholesterol and LDL-cholesterol concentrations were increased from 26.3 ± 8.1 to 1,485.0 ± 26.8 mg/dL and from 15.9 ± 5.9 to 1,383.8 ± 58.9 mg/dL, respectively, whereas triglyceride concentration increased from 88.3 ± 35.6 to 411.0 ± 154.5 mg/dL upon cholesterol feeding. Seventy-five percent of platelet aggregation inhibition was observed with 10 μM of polyamines in PRP of normal rabbits. Spermine inhibited platelet aggregation by 54% in PRP of hypercholesterolemic rabbits when ADP was used as agonist. The order of polyamine action was spermine > spermidine > putrescine. In addition, we found that platelet arginase activity and L-arginine content were unaltered upon hypercholesterolemia. sions results show that the polyamines putrescine, spermidine, and spermine have antagonist action in platelet aggregation and suggest a key role of polyamines in platelet aggregation under normal and hypercholesterolemic conditions.