An abnormal platelet membrane lipid composition in patients with low and high blood cholesterol.

Platelet lipid composition was determined in subjects with hypercholesterolemia (HC) (9.17 ± 2.15 mmol/L), hypocholesterolemia (HYPOC) (3.29 ± 1.01 mmol/L), and normocholesterolemic controls (NC) (5.29 ± 0.82 mmol/L). Lipid composition was quantitated in washed platelets by measuring platelet cholesterol (C) and phospholipid (PL) content, C/PL molar ratio and platelet PL phosphatidylcholine (PC) to sphingmyelin (SM) ratio. There was a significant increase and a significant decrease in C/PL molar ratio in subjects with HC and HYPOC compared to normals (0.74 ± 0.06 and 0.53 ± 0.06 vs 0.59 ± 0.04, p<0.01, respectively). These alterations were due to a significant change in platelet C content, whereas, platelet PL content was stable. PC/SM ratio was markedly decreased in HYPOC compared to NC (0.80 ± 0.18 vs 2.03 ± 0.18, p<0.01, respectively). These results indicate that blood cholesterol is a major determinant of platelet membrane lipid composition. This effect may be of concern in relation to a possible excess morbidity in patients not only with HC, but also with a low blood cholesterol.