Enhancement of thrombotic arterial occlusion following cholesterol feeding in the guinea-pig: a role for thromboxane A2.

We have developed a photochemical model to induce thrombotic occlusion of the guinea-pig femoral artery. Using this model, we investigated the effect of cholesterol feeding on arterial occlusion time in the guinea-pig. Animals were divided into two groups, one on standard diet and the other on standard diet containing 0.5% cholesterol for 3 weeks. The time for femoral artery occlusion was significantly shorter (p < 0.05) in cholesterol fed animals as compared to the control group. In vitro collagen-, U-46619- (a thromboxane A2 adenosine diphosphate analogue) and (ADP)-induced platelet aggregation responses in whole blood in cholesterol-fed animals were increased 13-, 10- and 4-fold, respectively. U-46619- and collagen-induced washed platelet aggregation responses were also significantly enhanced by cholesterol feeding (p < 0.01). Further, TXA2 generation by collagen-stimulated washed platelets in cholesterol-fed animals increased similar to the platelet aggregation responses. However, platelet-activating factor (PAF)-induced platelet aggregation in whole blood was relatively unaffected by cholesterol feeding. 11-dehydro TXB2 levels in plasma were increased significantly by cholesterol feeding. Our observations suggest that increased plasma TXA2 level and platelet aggregation response to TXA2 and stimulated TXA2 synthesis in platelets play a role in enhanced arterial occlusion in cholesterol fed guinea-pigs.