Human prostacyclin platelet receptors and platelet lipid composition

To assess the role of the cellular lipid environment in the expression of prostacyclin (PGI2) membrane receptors, PGI2 binding sites together with cholesterol and phospholipid content in platelets from 17 healthy subjects were investigated. Membrane receptors were investigated by a direct radioligand binding method using [3H]PGI2 as radiolabeled ligand. Significant negative correlations between PGI2 high-affinity receptors and platelet cholesterol content (r = -0.787, P less than 0.001) and platelet cholesterol/phospholipid ratio (r = -0.946, P less than 0.001) were observed; on the contrary phospholipid content was positively correlated with the number of high-affinity receptors (r = 0.610, P less than 0.01). These results indicate that physiological changes in platelet lipid composition can affect membrane receptor number.