Effect of diet-induced hyperlipidemia on in vitro-function of rabbit platelets

Abstract

Hyperlipidemia was induced in rabbits by feeding them a diet enriched with egg yolk for a minimum period of sixteen weeks. Platelets isolated from the blood of these rabbits and resuspended in Tyrode-albumin solution showed a significant increase in collagen- or thrombin-induced aggregation and serotonin release but not in aggregation induced by ADP. Collagen-induced platelet factor 3-availability was also greater with platelets from hyperlipidemic rabbits compared with platelets from control rabbits. There were no significant differences between the diet and control groups in platelet aggregation induced by ADP, collagen, or thrombin or serotonin release induced by collagen or thrombin in citrated platelet-rich plasma. With washed platelets there was no correlation between the percentage increase in aggregation induced by collagen or thrombin and the plasma cholesterol or triglyceride levels in hyperlipidemic or control rabbits. When washed normal rabbit platelets were resuspended in citrated plasma from a hyperlipidemic rabbit their response to aggregating or release-inducing stimuli was not significantly different from that observed when platelets from normal rabbits were resuspended in normal plasma. When washed normal platelets were incubated for 30 min in hyperlipidemic plasma at 37°C, isolated from the plasma and resuspended in Tyrode-albumin solution, their response to aggregating or release-inducing stimuli was not significantly different from that observed with normal platelets incubated in normolipidemic plasma. The findings indicate that diet-induced hyperlipidemia in rabbits may induce an intrinsic functional alteration of the platelets which cannot be readily reproduced by short-term in vitro exposure of platelets to hyperlipidemic plasma.