Lovastatin decreases plasma and platelet cholesterol levels and normalizes elevated platelet fluidity and aggregation in hypercholesterolemic patients

Abstract The lipid composition of whole platelets and the fluidity of platelet membranes, as well as the sensitivity of the cell to aggregation, were studied in type IIA hypercholesterolemic human subjects before and after treatment with lovastatin. Fourteen patients with primary hypercholesterolemia having initial cholesterol levels of 383 ± 52 mg/dL (mean ± standard deviation) were studied and compared with 21 control subjects having cholesterol levels of 187 ± 32 mg/dL. Lovastatin was administered orally at a starting dose of 40 mg daily. The dose was increased to 80 mg daily for eight patients who did not achieve the target cholesterol level of 200 mg/dL at 6 weeks. Serum cholesterol level was decreased by 37% following 20 weeks' administration of the drug. The fluidity of platelet membranes expressed in terms of the fluorescence anisotropy parameter was determined using the probe 1,6-diphenyl-1,3,5-hexatriene (DPH). When compared with platelets obtained from normocholesterolemic controls, platelets from hypercholesterolemic patients had a higher molar ratio of cholesterol to phospholipids ([ C / PL ] 0.86 ± 0.15 v 0.57 ± 0.06 for controls) and of phosphatidylcholine to sphingomyelin ([ PC / SM ] 2.64 ± 0.87 v 2.00 ± 0.15 for controls), enhanced fluidity (anisotropy parameter at 37°C of 0.892 ± 0.066 v 0.977 ± 0.065 for controls), and a greater tendency to aggregate (aggregation of 84.2% ± 6.3% v 78.5% ± 7.6% for controls). Lovastatin administration for 20 weeks to hypercholesterolemic patients markedly normalized platelet lipid composition ( C / PL , 0.58 ± 0.13; PC / SM , 1.84 ± 0.60), membrane fluidity (anisotropy parameter, 0.980 ± 0.033), and aggregation (aggregation, 75.9% ± 10.0%), suggesting that lovastatin treatment may attenuate the involvement of platelets in the pathogenesis of atherosclerosis.