EFFECT OF HYPERCHOLESTEROLEMIA ON PLATELET GROWTH-FACTORS

Evidence from several sources suggests that important interactions occ ur between platelets and low-density lipoproteins. This study was unde rtaken to find out if diet-induced hypercholesterolaemia affects the g rowth factor content in circulating platelets. Minipigs were fed eithe r normal diet supplemented with 2% cholesterol (n = 12) or normal diet alone (n = 12). After 4 months, mean platelet volume was significantl y lower (P < 0.05) and monocyte count was significantly higher (P < 0. 05) in the cholesterol group. Serum and intraplatelet levels of platel et-derived growth factor (BE homodimer) and transforming growth factor beta 1 were statistically unchanged after diet. Hypercholesterolaemia did not affect the proliferative effect of either serum or platelet l ysates on porcine vascular smooth muscle cells and Swiss-3T3 cells in culture. A significant positive correlation between Swiss-3T3 and smoo th muscle cell proliferation was present in both groups. These results suggest that the atherosclerosis-promoting effect of hypercholesterol aemia cannot be explained by its direct effect on smooth muscle cell p roliferation or by changes in serum or intraplatelet concentrations of growth factors.