Lipoproteins from normolipidemic and dyslipidemic subjects modify the thromboxane A2 generation by platelets in clotting human blood.

Abstract The study was performed to investigate the influence of lipoproteins (LP) on the thromboxane (TX) A 2 formation capacity of platelets in clotting whole blood in vitro. The different lipoprotein fractions VLDL, LDL, HDL 2 and HDL 3 were isolated from blood of normo- or dyslipidemic volunteers by ultracentrifugation. These lipoproteins were incubated in blood with different levels of serum total cholesterol (TC) taken from normolipidemics (TC 250 mg/dl), respectively. The amount of serum TXA 2 formed within 60 min at 37°C was measured by enzyme immunoassay. The results obtained show that the efficacy of separate LP fractions to influence the TXA 2 production depends not only on the type of LP fraction but also on the source of plasma used for isolation of LP and on the cholesterol level in the blood for incubation: LDL taken from normolipidemics or moderate hyperlipidemics inhibited the TXA 2 formation in blood from normolipidemics (P 2 production in blood from hyperlipidemics (P 2 fractions inhibited the TXA 2 formation in blood from normo- and hypercholesterolemics (P 2 in clotting blood from persons with moderate hypercholesterolemia. All HDL 3 fractions tested inhibited the TXA 2 formation in all types of blood used for clotting (P