Platelet and megakaryocyte changes in cholesterol-induced experimental atherosclerosis.

Rabbits were fed either 2 g cholesterol in 10 ml olive oil daily with normal diet (n = 5) or normal diet alone (n = 5). After 12 weeks, the cholesterol-fed animals had developed fatty plaques involving 24% +/- 4% of the surface area of the aorta; the control animals had none. Mean platelet volume was significantly smaller (p less than 0.04) in the cholesterol-fed animals (4.1 +/- 0.3 fl) compared with the controls (4.8 +/- 0.4 fl). The heterogeneity of the average volume distributions of the two groups, characterized by the statistical parameters of the coefficient of variation, skewness, and kurtosis, was also significantly different. Platelet count was significantly higher (p less than 0.001) in the cholesterol-fed group (7.48 +/- 1.06 x 10(11) platelets/liter blood) compared to the control group (4.86 +/- 0.60 x 10(11) platelets/liter blood). Mean megakaryocyte cytoplasmic volume was significantly larger (p less than 0.001) in the cholesterol-fed rabbits (12,262 +/- 1485 fl) compared with controls (6,814 +/- 761 fl). The range of cytoplasmic volumes was also significantly increased in the cholesterol-fed rabbits. A significant (p less than 0.01) increase in mean megakaryocyte nuclear volume in the cholesterol-fed animals was accompanied by a nonsignificant increase in mean nuclear DNA content: 30.2 +/- 3.7 N compared with a control value of 23.6 +/- 4.0 N. This evidence indicates that a high cholesterol diet in rabbits is associated with changes in platelet production from megakaryocytes as well with as the development of atherosclerosis.