1977 Volume 23 Issue 2 Pages 101-113
Male guinea pigs fed a cholesterol diet for 1-8 weeks showed a marked increase in platelet aggregation induced by ADP. Analyses of lipids indicated that dietary cholesterol resulted in highly signi-ficant increases in plasma cholesterol, β-lipoprotein and phospholipid levels, and platelet cholesterol contents. Plasma triglyceride levels in cholesterol-fed animals increased significantly only at the 8th week of feeding. Platelet phospholipid levels in cholesterol-fed animals increased significantly at the 2nd and 4th week of feeding. There were statistically insignificant increases in plasma and platelet free fatty acid. Fibrinogen levels in cholesterol-fed animals showed an increase at the 2nd and 4th week of feeding, but clotting tests, such as prothrombin time, recalcifi-cation time and Stypven time, were not changed. When platelets from animals fed on a control diet were exposed to plasma from cholesterol-fed animals, there was a notable increase in platelet aggregation in comparison with plasma from animals fed on a control diet. An increase of platelet aggregation was also observed, when platelets from cholesterol-fed animals were mixed with the plasma from not only cholesterol-fed animals but also animals fed on a control diet. As the cholesterol in plasma and platelets was assumed to be a possible factor in the increase of platelet aggregation, β-lipoproteins (cholesterol-rich proteins) were isolated from plasma of cholesterol-fed animals and animals fed on a control diet, and β-lipoprotein fractions were found to cause a marked increase in platelet aggregation induced by ADP. The results of this study indicate that cholesterol feeding causes an increase of platelet aggregation, and that the causative factor of the increase is assumed to be β-lipo-proteins.
