Abstract
On our previous study of experimental atherosclerotic rabbits aortic prostacyclin production was significantly decreased and plasma lipoperoxide levels were elevated.
In the present study, the experimental atherosclerotic rabbits were produced by the feeding of 0.5% cholesterol containing diet. On these models platelet functions, i. e., ADP sensitivity, prostacyclin sensitivity and platelet malondialdehyde (MDA) formation were investigated.
Tissue (liver and aorta) lipoperoxide levels were also studied.
Following results were obtained.
(1) Platelets from rabbits fed with cholesterol rich diet had decreased sensitivity to prostacyclin.
The amount of prostacyclin required for 50% inhibition of platelet aggregation induced by 2.5μM ADP were 0.730±0.050ng/ml (mean±SD) in control rabbit platelets 1.157±0.087ng/ml in rabbits had with 0.5% cholesterol containing diet for 1 month, 1.247±0.145ng/ml in rabbit platelets had with 0.5% cholesterol containing diet for 2 months.
(2) The tendency of increased sensitivity of platelets to ADP aggregation was seen though statistically not significant.
From the magnitude of platelet aggregation induced by various concentration of ADP (0.3-4.0μM), the concentration of ADP required for the half maximum aggregation were 1.12±0.21μM in control rabbit platelets and 0.74±0.17μM in rabbit platelets fed with 0.5% cholesterol diet for 2 months.
(3) MDA formation of platelets were 0.17±0.049nmol/3×108 plt. in control and 0.168±0.036 nmol/3×108 plt. in cholesterol fed rabbits.
These results suggest the decreased aortic prostacyclin production and the dereased platelet sensitivity to prostacyclin may contribute the development and progression of atherosclerotis.
